The 43rd International Symposium on Lattice Field Theory (Lattice 2026)

26 Jul 2026, 14:00 → 1 Aug 2026, 14:30 US/Eastern

University of Maryland, College Park

The 43rd International Symposium on Lattice Field Theory (Lattice 2026) will take place at the University of Maryland, College Park, USA, from July 26 to August 1, 2026. The conference brings together researchers from around the world to present and discuss recent theoretical, algorithmic, and computational advances in lattice field theory, with a primary emphasis on Quantum Chromodynamics (QCD). Reflecting the central role of high-performance computing, the program also includes developments in software, computing architectures, artificial intelligence and machine learning, and algorithms for quantum computing.

2026-KWA-Nomination-Form.docx

First-circular.pdf

Second-circular.pdf

Third-circular.pdf

Sunday 26 July

18:30 → 20:30 Registration

18:30 → 20:30 Welcome reception

Monday 27 July

08:00 → 09:00 Registration

09:00 → 10:30 Plenary session

Convener: Aida El-Khadra (University of Illinois Urbana-Champaign)

09:00 Welcome and opening remarks I

Speaker: Prof. Zohreh Davoudi (University of Maryland)

Openning-remarks.pdf

09:05 Welcome and opening remarks II

Speaker: Prof. Patrick O'Shea (University of Maryland, College Park)

09:15 Lattice QCD for Quark-Flavour Physics

The quark-flavour sector remains one of the most promising avenues for uncovering physics beyond the Standard Model, with an experimental programme set to sharpen its precision, and extend the set of measured quantities, well into the 2040s. Matching this requires lattice QCD to tackle existing and new formal challenges, and to work in ever-closer partnership with experiment.
I will survey these developments, before turning to the determination of key CKM matrix elements, where longstanding puzzles continue to challenge our understanding. I will also take a look at other new developments such as long-distance contributions to rare decay processes, where lattice methods are beginning to bring first-principles control to amplitudes once left to model-dependent estimates.

Speaker: Andreas Juttner (CERN)

Lattice 2026 Flavour.pdf

10:00 The recent precision determination of $\alpha_s(m_Z)$ by the ALPHA collaboration

The strong coupling, $\alpha_s(m_Z)$, is a fundamental parameter of the Standard Model and its precise determination is of central importance to particle physics. It is ubiquitous in the description of hadron collider physics: its uncertainty directly affects the control of initial parton states, e.g. in $pp$-collisions at the LHC, and limits precision studies of Higgs boson production and decay rates. The high energy physics community has set the ambitious goal to reach per mille precision over the next 10-20 years.
A significant milestone is the precision result, $\alpha_s(m_Z)=0.11876(58)$, recently published by the ALPHA collaboration. It was obtained by combining two complementary methods to first determine the $\Lambda$-parameter in 3-flavour QCD, without relying on perturbation theory at low energies. Perturbation theory is used in the matching to 5-flavour QCD across the charm and bottom thresholds, with uncertainties estimated both perturbatively and non-perturbatively. The total error of 5 per mille is still statistics dominated and leaves some room for further improvement.

Speaker: Stefan Sint (Trinity College Dublin)

lat26_sint.pdf

10:30 → 11:00 Coffee break

11:00 → 12:30 Plenary session

Convener: William Detmold

11:00 Smeared spectral function: opportunities and challenges

A broad class of physical observables can be expressed in terms of smeared spectral functions. Important examples include the hadronic vacuum polarization contribution to the muon g−2, hadronic τ decays, inclusive semileptonic B and D decays, and amplitudes for rare processes such as B→Kl+l−. In recent years, a variety of methods have been proposed to reconstruct or constrain such spectral functions from Euclidean correlators and related inputs. However, the inverse problem is intrinsically ill-posed, making it difficult to obtain fully reliable, model-independent results with controlled uncertainties. In this talk, I will summarize recent developments, discuss the opportunities offered by smeared spectral observables, and highlight the main challenges that remain.

Speaker: Shoji Hashimoto (KEK)

smeared spectrum.pdf

11:30 Recent Progress in Lattice Determination of Radiative Corrections in Hadronic Processes

As precision tests of the Standard Model enter the sub-percent era, radiative corrections in hadronic processes become indispensable theoretical inputs for identifying small deviations between theory and experiment that could signal new physics. Theoretical predictions of radiative corrections are highly challenging, as they intertwine long-distance QED effects with nonperturbative QCD and therefore require lattice QCD+QED calculations with controlled finite-volume systematics. In this talk, I will review recent progress in lattice determinations of radiative corrections, with a focus on meson leptonic decays and related radiative decay processes. I will also summarize broader developments in lattice QCD+QED studies and discuss future opportunities for phenomenologically important applications.

Speaker: Xin-Yu Tuo (Brookhaven national laboratory)

Lattice2026.pdf

12:00 Algorithms and machines for lattice field theory research

I will present the evolution of the machines powering the lattice field theory. I will review recent developments in algorithm and software, present performance results from today's systems, and discuss the future of high performance computing and its impact on our field.

Speaker: Xiao-Yong Jin

plenary_jin.pdf

12:30 → 14:00 Lunch break

14:00 → 15:40 Algorithms and artificial intelligence

Convener: En-Hung Chao (JGU Mainz)

14:00 Reducing the residual mass of domain-wall fermions using machine learning

Domain-wall fermions provide a lattice formulation that preserves chiral symmetry to a high degree by introducing an additional fifth dimension. In practical simulations, however, the extent of this direction must remain finite, which leads to residual chiral symmetry breaking characterized by the residual mass. Increasing the fifth-dimensional size can reduce this effect, but it also significantly raises the computational cost. To address this trade-off, we develop a machine-learning-based framework that optimizes the domain-wall fermion parameters so as to minimize the residual mass while keeping the fifth dimension short. Our approach aims to reproduce the improved chiral properties normally obtained with a larger fifth-dimensional extent, thereby enabling more efficient lattice simulations without a substantial increase in computational resources.

Speaker: Shunsuke Yasunaga (Institute of Science Tokyo / RIKEN)

lattice_2026_yasunaga.pdf

14:20 Non-perturbative tuning of relativistic heavy quarks using machine learning in lattice QCD

In this talk we introduce a machine learning approach to tune an effective relativistic heavy quark action for applications in lattice QCD.
The effective action is the so-called "RHQ" action, which has three open parameters that require non-perturbative tuning to match physics observables associated with Lorentz symmetry, spin-averaged masses, and hyperfine splittings in charmonium and bottomonium systems. We reformulate the tuning procedure as a supervised-learning problem to construct a non-linear map between the action parameters and the tuning observables.
We demonstrate the procedure on two ensembles generated within the OpenLat Initiative. The learned map accurately reproduces the tuning observables in the parameter region of interest. The approach streamlines RHQ tuning on new ensembles and supports future calculations in heavy-hadron spectroscopy.

Speaker: Thamirys de Oliveira (National Yang Ming Chiao Tung University)

[deOliveira]Lattice_2026_split_jul27.pdf

14:40 Machine-Learning-Accelerated Multigrid Setup for Lattice QCD Dirac Solves

Gauge-field generation in lattice QCD is dominated by repeated solves of the Dirac equation. While multigrid preconditioners reduce solve costs significantly, their expensive setup phase limits overall efficiency. We introduce a gauge-equivariant neural network that accelerates this setup by using approximate low modes from previous configurations, exploiting the autocorrelation along the Markov chain. We tested the method on quenched ensembles at beta=6 with two lattice sizes (8^3 x 16 and 16^3 x 32). Comparing our setup method to a standard multigrid setup with similar computational cost, we find that our setup method leads to a substantially faster multigrid solve. Remarkably, networks trained on the smaller volume generalize to the larger lattice without the need for retraining. These results demonstrate a promising path toward more efficient large-scale lattice QCD simulations.

Speaker: Simon Pfahler (University of Regensburg)

Lattice26_Simon_Pfahler.pdf

15:00 The Renormalization-Group Preconditioned Conjugate Gradient for Domain Wall Fermions

We report on the current status of the renormalization-group preconditioned conjugate gradient (RGPCG) for domain wall fermions (DWF), an algorithm that leverages the correspondence between low modes of the Dirac operator on ensembles related by RG-blocking to produce a preconditioner with small setup overhead. We have studied this approach for Möbius DWFs on a fine $a^{-1} = 2$ GeV lattice, with a preconditioner that uses low modes of an RG-blocked coarse $a^{-1} = 1$ GeV lattice, which are much cheaper to compute. While preconditioning with an approximate coarse-lattice solution effectively deflates the low mode space, the prolongation introduces unwanted noise in the higher modes, limiting the preconditioner's utility. Motivated by the equivalence of physical observables on the RG-related fine and coarse lattices, and the exponential localization of chiral low modes of the DWF operator on the boundaries of the fifth dimension, we find that restricting the preconditioner to these physical chiral components reduces noise contamination from higher modes while also lowering the deflation cost by a factor of $L_s$.  Our preliminary results indicate that the improvement in convergence rate exceeds the preconditioner cost, making this a candidate for use in ensemble generation.

Speaker: Mr Jonah Eick (Columbia University)

Lattice_2026_Presentation final.pdf

15:20 Algorithms for domain wall fermions

We study and visualize the process of topology change in field transformation hybrid Montecarlo, correlating gauge and fermion forces with changes in the chiral mode structure of the Domain Wall fermion operator. We see that in each trajectory there are multiple changes of topology by both flowed gauge measures and by the Domain wall fermion index. These appear to correspond to small scale gauge structures and rapid localized reversion. This suggests both a mechanism how the FTHMC heuristic may help address tunneling rates, and perhaps could lead to improved formulations of the algorithm

Speaker: Dr Peter Boyle

Lattice2026Boyle.pdf

14:00 → 15:40 Hadronic and nuclear spectrum and interactions

Convener: Takumi Doi

14:00 Improving hadron creation operators for charmonium, glueballs and baryons

Constructing hadron creation operators which properly sample the finite-volume energy spectrum is a fundamental step in lattice QCD spectroscopy and scattering calculations. Operators enabling access to spectrum information from correlation functions at early temporal separations are extremely advantageous, particularly when the signal-to-noise problem is severe. We present improved operator constructions for charmonium, glueball and baryon spectroscopy which exhibit these advantages. Novelties of our work include the extension of the distillation profiles framework to baryon and multi-meson calculations, as well as an efficient implementation of glueball-like operators which retain angular momentum information from the continuum.

Speaker: Juan Andres Urrea Nino (Trinity College Dublin)

Lattice26-Urrea-Monday.pdf

14:20 A Novel Quark Smearing Technique and its Application to Distillation

We introduce a novel quark smearing method designed to project the quark field onto a low-energy subspace efficiently. This smearing method is employed to compute sparse estimators of multi-hadron correlation functions. While the signal for the ground state is found to be the same as obtained from full correlation functions, the computational cost is drastically reduced. Furthermore, we implement these basis functions within exact and stochastic distillation frameworks. We show that both single- and multi-hadron correlation functions can efficiently be evaluated within this framework, yielding substantially reduced contraction costs and memory storage requirements without compromising signal quality.

Speaker: Nilmani Mathur (Tata Institute of Fundamental Research)

Lattice26_NMathur.pdf

14:40 A framework for the automated evaluation of two- and three-point correlation functions using distillation

We present a suite of software for every part of the workflow for evaluating correlation functions on an ensemble of gauge configurations: the construction of irreducible hadron operators, the enumeration of Wick contractions, and the resultant tensor contractions. The workflow is illustrated for correlators between one-, two- and three-hadron operators present in the excited nucleon spectrum using a small-volume CLS lattice at $m_{\pi}=280\,{\rm MeV}$.

Speaker: John Bulava

bulava_lattice.pdf

15:00 Noise reduction for disconnected diagrams

We present a noise reduction technique for disconnected diagrams in lattice QCD correlation functions, using the $\eta$ meson as an illustrative example. The method constructs a noise-reduced interpolating operator by subtracting a truncated-gauge-configuration estimate of the disconnected contribution. The truncated configuration restricts the gauge field to a finite time-slice window around the operator location, yielding a valid gluonic operator whose subtraction reduces disconnected-diagram noise without introducing additional systematic error. The effective time separation between the two operators is reduced by the tunable parameter $\Delta t$, but the improved signal overlap compensates. We discuss the method, its properties, and preliminary numerical results.

Speaker: Luchang Jin (Univeristy of Connecticut)

luchang-jin-noise-reduction-on-disconnected-diagrams.pdf

15:20 Wave-functions and operator optimization for two hadrons in Lattice QCD

A systematic framework for constructing optimized interpolating operators strongly coupled to QCD two-particle states is developed, which is achieved by incorporating inter-hadron spatial wavefunctions. To efficiently implement these operators in lattice QCD, a novel quark smearing technique utilizing noise vectors is proposed. Applied to the $\Omega_{ccc}\Omega_{ccc}$ system, these optimized operators prove superior to combinations of limited plane-wave operators, enabling the resolution of distinct eigenstates separated by only $\sim 5$ MeV near the threshold $2m_{\Omega_{ccc}} \simeq 9700$ MeV. This exceptional resolving power opens new possibilities for studies of a wide range of hadronic systems in QCD.

Speaker: Sinya Aoki

Lattice2026.pdf

14:00 → 15:40 Quantum computing and quantum information

Convener: Jesse Stryker (Lawrence Berkeley National Laboratory)

14:00 Some Aspects of Quantum Simulations for Bosons and D-brane Scattering

Quantum simulations provide a promising framework for studying the real-time dynamics of interacting quantum systems beyond the reach of classical computation. In this talk, we present several aspects of quantum simulations for systems of bosons, including a toy model for D-brane scattering. We describe an efficient digitization and discuss how the evolution of the wave function's mean position and spatial spread provides an intuitive picture of the scattering process. We conclude by outline possible generalization toward quantum simulations of D-brane dynamics, with potential relevance for non-perturbative aspects of quantum gravity and the gauge/gravity correspondence.

Speaker: Emanuele Mendicelli (University of Liverpool (United Kingdom))

Mendicelli_E__Lattice_2026_.pdf

14:20 Observation of quantum-field-theory dynamics on a spin-phonon quantum computer

Quantum simulation is a promising approach to study out-of-equilibrium dynamics of quantum gauge field theories, particularly in regimes where classical methods become intractable. Mapping bosonic (gauge) degrees of freedom onto qubits requires truncating their infinite dimensional Hilbert space, leading to errors that grow with system energy and simulation time, and resulting in a large qubit and gate overhead in fully digital schemes. An alternative method is to augment the qubit-based quantum computer with controllable bosonic degrees of freedom, enabling hybrid architectures that naturally implement qubit, bosonic and qubit-bosonic gates. In this work, we simulate nonequilibrium dynamics of a (1+1)-dimensional Yukawa model, a fermion-boson quantum field theory, on a trapped-ion platform where qubits are encoded in the ions’ internal levels and bosons in their motional modes. The fermion- and boson-occupation state probabilities were measured and found to be in good agreement with classical simulations, even for high phonon occupations. This hybrid approach bypasses the need for a large qubit overhead, and removes truncation errors. Our results, therefore, open the way to achieving demonstrable quantum advantage in qubit-boson quantum computing.

Speaker: Vinay Vikramaditya (University of Maryland, College Park)

Observation of quantum-field theory dynamics on a spin-boson Lattice 2026 Final.pptx

14:40 Simulating lattice gauge theories on hybrid qubit-qumode quantum platforms

We present a versatile quantum computing framework designed to simulate real-time dynamics on emerging hybrid hardware platforms that provide simultaneous access to both discrete (qubits) and continuous (qumodes) quantum resources. This framework leverages continuous-variable bosonic modes to represent the infinite-dimensional Hilbert space of gauge fields, integrated with qubits to represent fermionic matter for lattice simulations. We outline both Abelian and non-Abelian implementations in 2+1 dimensions, and explore error-correction pathways enabled by a new class of non-polynomial trigonometric gates.

Speaker: Tommaso Rainaldi (Stony Brook University)

Rainaldi_Lattice2026.pdf

15:00 Measurement-based simulation of lattice gauge theory dynamics with adaptive quantum circuits on a trapped-ion processor

Real time dynamics of lattice gauge theories are difficult to access with Euclidean Monte Carlo methods and challenging to implement on quantum devices, where noise can drive states out of the gauge invariant sector. I will present an experimental realization of measurement based quantum simulation (MBQS) for a $(2+1)$ dimensional $\mathbb{Z}_2$ lattice gauge theory on Quantinuum's H2 trapped ion processor, following the MBQS construction of Sukeno and Okuda, SciPost Phys. 14, 129 (2023).
In MBQS, a resource state tailored to the target model replaces a conventional gate sequence. Its connectivity follows the spacetime locality of the lattice field theory, while adaptive measurements during the circuit consume the resource and implement Hamiltonian time evolution. Using measurement, reset, and re-entanglement, we realize virtual three dimensional cluster resources with hundreds of virtual resource state qubits from a finite register of physical ions.
For this gauge theory resource, the same measurement record that drives the evolution also provides one form symmetry syndromes, which diagnose leakage from the gauge invariant sector. We use these syndromes for postselection and observe improved agreement with ideal Trotterized dynamics, together with coherent evolution of plaquette and loop observables.

Speaker: Takuya Okuda (University of Tokyo)

okuda.pdf

15:20 Real Time GEVP on Quantum Hardware

Quantum computers can produce real time correlators of field theories. We adapt the generalized eigenvalue problem to these real-time correlators in order to extract energy eigenvalues. We test the method with both simulations in classical computers and on actual quantum hardware. We are able to resolve several low-lying energy levels, in agreement with exact diagonalization results. We also compare our results the energy level extractions by Fourier transforming the time-dependence of the signals and show that our method is far more efficient.

Speaker: Valery Simonyan (University of Maryland)

Realtime GEVP-v3.pdf

Realtime GEVP-v3.pptx

14:00 → 15:40 Quark and lepton flavor physics

Convener: Andre Walker-Loud (Lawrence Berkeley National Laboratory)

14:00 The Muon g-2 HVP contribution from the BMW/DMZ collaboration

In this talk I will present updated results on the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. I will discuss several window observables, the details of the continuum extrapolation and of other sources of systematic uncertainties.

Speaker: Balint Toth (University of Wuppertal)

tothb_lat2026.pdf

14:20 Towards the smeared R-ratio with Nf=2+1+1 highly improved staggered quarks

In this talk we present the ongoing effort of the Fermilab Lattice and MILC Collaboration to compute the smeared $R$-ratio using $N_f=2+1+1$ HISQ gauge-field ensembles. We discuss closure tests for mock data which incorporate taste-breaking and finite-volume effects to mimic real light-quark connected vector isovector correlation functions. This enables a detailed comparison between different spectral reconstruction methods, suitably adapted to include staggered oscillations, paving the way to real lattice data applications with controlled systematic errors.

Speaker: Matteo Saccardi (Colorado State University)

msaccardi_rratio.pdf

14:40 Nevanlinna-Pick interpolation from uncertain Euclidean correlation functions

The calculation of inclusive observables remains a significant challenge for lattice QCD, where the inverse problem of relating Euclidean-space data to real-time, multi-particle processes is inherently ill-posed. This work further develops a potential first-principles solution to this inverse problem which uses Nevanlinna-Pick interpolation to determine inclusive decay rates from uncertain data. Here we present a method that begins with uncertain Euclidean space-time correlation function data, which are then Laplace transformed with $O(a^2)$ discretization errors, followed by the Nevanlinna-Pick interpolation described above.

Speaker: Sarah Fields (Columbia University)

Sarah_Fields_Lattice_2026_talk.pdf

15:00 Bootstrapping spectral functions

The problem of reconstructing spectral densities from noisy Euclidean-time Monte-Carlo data provides a valuable test-bed for investigating real-time and inclusive observables, and sign problems more broadly. In this talk, I will discuss the causal bootstrap, a new method for spectral reconstructions that unifies several approaches, including analyticity-based methods (Nevanlinna-Pick interpolation, moment problems), convex programming methodologies, and generalizes linear reconstruction methods, such as the commonly used Hansen, Lupo, and Tantalo (HLT) method. The causal bootstrap uses tools originally developed for the conformal bootstrap in order to provide rigorous bounds on smeared spectral functions while enforcing the positivity of the underlying spectral density, and is directly applicable to noisy Monte-Carlo data. I will discuss the methods and their relations, as well as initial results on applying the causal bootstrap to semi-inclusive tau decay on RBC-UKQCD domain wall fermion ensembles.

Speaker: Ryan Abbott (Columbia University)

AbbottRyanLattice2026.pdf

15:20 Kernel transformations for smeared spectral functions

Smeared spectral functions play a central role in the extraction of many inclusive hadronic observables. This talk will discuss recent work on kernel transformations, a framework for transforming between smeared spectral functions computed using different smearing kernels. Analytic and regulated solutions will be presented, with an emphasis on controlling the effect of any intermediate approximation directly from the smeared input data.

Speaker: William Jay (Colorado State University)

wjay_lattice2026.pdf

14:00 → 15:40 Software development and machines

Convener: Xiangyu Jiang (Indiana University)

14:00 A Stabilized FP16 Mixed-Precision Solver

We present a stabilized FP16 mixed-precision solver. Because the dynamic range of FP16 is much smaller than that of FP32, straightforward use of FP16 arithmetic may suffer from underflow and overflow. To address this issue, we introduce a rescaling procedure for the working vectors. The performance of the solver is evaluated on the Supercomputer Fugaku, which provides native FP16 SIMD support, and compared with that of a conventional FP32-based mixed-precision solver.

Speaker: Dr Issaku Kanamori (R-CCS, RIKEN)

lattice2026.pdf

14:20 Toward Compute-Bound Lattice-QCD Software

Historically, the cost of lattice-QCD calculations was dominated by applications of the Dslash matrix on a single right-hand side, which is constrained by memory-bandwidth limits to run at a small fraction (10-20%) of the available processing power.  The advent of multigrid methods and multi-right-hand-side solvers mean that these limits are no longer the binding constraints they once were.  Additionally, for nuclear physics calculations, a substantial fraction of the total computational cost is in the contractions of quark propagators into correlation functions.  I will present software developments that I have made to help accelerate these, and I will also discuss the role of generative AI in this code development.

Speaker: Anthony Grebe (University of Maryland, College Park)

slides.pdf

14:40 Portability without Code Changes: Scaling QDP-JIT/Chroma via LLVM across NVIDIA, AMD, and Intel GPUs

Maintaining software portability across diverse accelerated hardware architectures remains a critical challenge for the lattice QCD community. The QDP-JIT library addresses this by providing a transparent, drop-in replacement for QDP++, enabling Chroma applications to run with high efficiency on modern GPUs without requiring any modifications to high-level code.

In this work, we present the evolution of QDP-JIT to a modern compiler infrastructure based on the LLVM IR builder API. Leveraging this infrastructure, we have expanded QDP-JIT beyond its initial NVIDIA support. We detail the integration of the AMDGPU backend and report on our recent efforts targeting Intel GPUs via SPIR-V and the Intel Level Zero runtime API.

We demonstrate the production readiness of this cross-platform stack using full Hybrid Monte Carlo (HMC) simulations featuring $2+1$ dynamical flavors of Wilson Clover fermions at near-physical pion masses on the Aurora supercomputer. While the computationally heavy two-flavor solves are offloaded to the SYCL-based QUDA multigrid solver, Amdahl's law dictates that the remaining HMC operations rapidly dominate the overall trajectory time if left on the CPU. We show how QDP-JIT successfully shifts these remaining execution paths to the Intel GPUs to run smoothly alongside QUDA, bringing down the total trajectory time significantly and establishing a highly efficient, portable pipeline across all three major GPU manufacturers.

Speaker: Frank Winter (Jefferson Lab)

winter2.pdf

15:00 PerfAdvisor: An LLM-based Agent for Diagnosing Bottlenecks from GPU Systems Profiles

We introduce PerfAdvisor, a lightweight Python package that uses an LLM-driven agent loop to diagnose GPU performance bottlenecks from supercomputer profiles. Modern HPC profiles contain millions of events across kernels, MPI calls, memory transfers, and idle gaps, making manual diagnosis slow and expert-intensive. PerfAdvisor automates this process by producing ranked, evidence-grounded bottleneck hypotheses and concrete mitigation suggestions in minutes. PerfAdvisor supports profiles from AMD ROCm Systems Profiler and NVIDIA Nsight Systems. It segments each profile into execution phases, computes summary metrics, and gives an LLM agent access to local, read-only tools for top-kernel summaries, idle-gap histograms, MPI and memory-transfer summaries, NVTX/ROCTx summaries, per-rank imbalance scoring, and arbitrary SQL queries. The agent iteratively gathers evidence until it returns ranked diagnoses with suggested fixes. Multiple LLM backends are supported, and prompt caching reduces token cost by up to 80%. We validate PerfAdvisor on NERSC Perlmutter using a CUDA benchmark suite with eight known performance pathologies and on OLCF Frontier using an analogous HIP benchmark suite. PerfAdvisor identifies the primary bottleneck in all eight cases with strong coverage of ground-truth mitigation strategies. In a MILC/QUDA lattice-QCD case study on NERSC Perlmutter, PerfAdvisor correctly diagnosed host-staged halo exchange and recommended GPUDirect RDMA, which reduced wall time by 43%.

Speaker: Leon Hostetler (Indiana University)

Hostetler_PerfAdvisor.pdf

15:20 First experiences operating and using ILDG 2.0

The International Lattice Data Grid (ILDG) is a global infrastructure for data sharing. It currently mainly aims for sharing ensembles of gauge field configurations. We present the status of the redesigned version of this infrastructure (ILDG 2.0), together with first user-experiences. A short live demonstration of basic functionalities will be carried out.

Speakers: Gunnar Bali (Universität Regensburg), Giovanni Pederiva (FZ Jülich)

ildg-lattice-2026.pdf

14:00 → 15:40 Standard-Model parameters

Convener: Curtis Peterson (Michigan State University)

14:00 Renormalization of vector and axial-vector currents for three flavor exponential-clover improved Wilson fermions

We present an update on the determination of renormalization constants and improvement coefficients for exponential-clover improved Wilson fermions in the coupling regime of interest for the large volume simulations of the OpenLat initiative ($a\approx 0.034-0.12\,{\rm fm}$). Particular focus is put on the renormalization of the non-singlet vector current using a massless renormalization scheme to determine the renormalization constant $Z_{\rm V}$ and its massive improvement coefficients $b_{\rm V}$ and $\bar{b}_{\rm V}$. Furthermore, we present an update on the improvement coefficient $c_{\rm A}$ and results on the renormalization of the non-singlet axial-vector current, $Z_{\rm A}$.

Speaker: Justus Kuhlmann (ETH Zürich)

LATTICE_2026_expWF.pdf

14:20 Renormalization and Improvement Conditions from Flowed Fermion Fields

Non-perturbative determinations of renormalization and improvement coefficients are an integral part of the continuum limit of lattice calculations. We explore an alternative strategy that uses composite operators at positive flow time as probes together with finite axial Ward identities to resolve the mixing due to the breaking of chiral symmetry generated by Wilson-like fermions. The resulting conditions lead to relations between gauge-invariant off-shell two-point functions in coordinate space. I will present numerical results of the aforementioned strategy in the setting of twisted mass fermions. As a first simplified example, I discuss results regarding the extraction of the critical mass and \mathcal{O}(a)-improvement coefficients associated with the flow. Additionally, the extraction of the ratio of the renormalization constants of the non-singlet axial and vector current, as well as the non-singlet scalar and pseudo-scalar density, will be presented. The extension to the determination of the ratio of renormalization constants of the effective electroweak Hamiltonian will be discussed, with hopes to be used in an ongoing project to perform a measurement of the isospin-breaking corrections to the tau decay rate. This work is done with ETMC and RC* collaborations.

Speaker: Lukas Holan (Humboldt University of Berlin)

main.pdf

14:40 Light and strange quark masses in $N_{f} = 2 + 1$ QCD with Wilson-type fermions.

We report on the status of an ongoing determination of the light and strange quark masses in QCD with $N_{f}=2+1$ dynamical flavours. Using CLS gauge ensembles, we employ a combination of a unitary non-perturbatively $\mathrm{O}(a)$-improved Wilson setup and a mixed-action approach with Wilson twisted-mass quarks at maximal twist in the valence. Bare quark masses are extracted from the PCAC relation in the pure Wilson setup and via the matching condition between the sea and valence sectors for the case of the mixed action. Scale setting is performed using the same mixed-action approach. Non-perturbative mass renormalisation at a hadronic scale and renormalisation-group running to the perturbative regime employ the Schrödinger functional scheme, enabling a well-controlled conversion to the $\overline{\mathrm{MS}}$ scheme. The analysis covers five values of the lattice spacing, down to $a \sim 0.038\,\text{fm}$, and pion masses reaching the physical value, enabling a systematic study of discretisation and chiral extrapolation uncertainties.

Speaker: Fernando Pérez Panadero (IFT-UAM/CSIC)

FPanadero_MD.pdf

15:00 Spectral reconstruction of the inclusive tau decay-rate with $C^*$ boundary conditions

Current discrepancies between inclusive and exclusive determinations of the CKM matrix-element $V_{us}$ necessitate the inclusion of isospin-breaking effects to reach sub-percent precision. Here we present some results of an exploratory study of the determination of the inclusive hadronic decay-rate of the tau lepton without neglecting isospin-breaking effects. To allow charged states to propagate in a finite volume, we use $\mathrm{QCD}+\mathrm{QED}$ ensembles with $C^*$ boundary conditions. Our non-perturbative approach will be complemented with a RM123 study by our collaborators at the ETMC. We use a single $\mathrm{RC}^*$ ensemble at a lattice spacing of $a=0.0539(2)\,\mathrm{fm}$ on a $64\times 32^3$ lattice with $m_\pi\approx380\,\mathrm{MeV}$. We calculate the necessary $2$- and $4$-point functions that enter the spectral reconstruction in a partially-quenched set-up and describe how this data can be used in the HLT-method to determine the decay-rate.

Speaker: Erik Bäske (Humboldt-Universität zu Berlin)

Presentation.pdf

15:20 Hadronic running of the electromagnetic coupling: comparisons of perturbative and lattice results above 1GeV

The electromagnetic coupling at the $Z$ pole, $\alpha_{\text{em}}(M_Z^2)$, is a key input for electroweak precision tests and searches for physics beyond the Standard Model. Fully exploiting the potential of future collider experiments will require a significant reduction of the theoretical uncertainties on this quantity. The dominant source of uncertainty stems from the hadronic running of the electromagnetic coupling, which can be addressed through a hybrid approach combining lattice QCD results at low energies with perturbative QCD at high energies. In this contribution, I present preliminary results for the comparison between the perturbative running of the hadronic contribution to $\alpha_{\text{em}}$ and lattice QCD results from the BMW collaboration.

Speaker: David Mason (JSC)

Lattice2026-6.pdf

14:00 → 15:40 Structure of hadrons and nuclei

Convener: Mr Rui Zhang (University of Maryland)

14:00 Parton Distribution Functions of the Nucleon from Twisted Mass Fermions with Physical Pion Mass

We present the unpolarized and helicity Parton Distributions (PDFs) of the nucleon using an ensemble of $N_f$=2+1+1 twisted mass clover-improved fermions with masses tuned to their physical values and lattice spacing of $a=0.080$ fm. We analyze seven momentum boosts up to $P_z=1.69$ GeV. At boost $P_z=1.21$ GeV we analyze three source-sink separations, in order to investigate possible excited state contamination. We investigate both LaMET and Short Distance Factorization to obtain the light-cone PDFs and their moments, respectively. Within the LaMET framework, we investigate an alternative method for the reconstruction of the x-dependent quasi-distributions using Bayes-Gauss-Fourier Transform and compare it to Backus-Gilbert.

Speaker: Gabriele Pierini (The Cyprus Institute, TU Berlin)

PDFs_Pierini_Lattice26.pdf

14:20 Proton GPDs from lattice QCD at the physical point

We present a calculation of the $x$ dependence of quark GPDs for the nucleon using an ensemble of $N_f$=2+1+1 twisted mass clover-improved fermions with masses tuned to their physical values and a lattice spacing of $a=0.080$ fm. We use matrix elements of nonlocal operators at several values of the momentum boost up to 1.69 GeV, enabling the extraction of GPDs in both the large-momentum effective theory (LaMET) and short-distance factorization (SDF). The matrix elements have momentum transfer between the initial and final states and are obtained in an asymmetric kinematic frame, which offers high computational efficiency. The matrix elements are parametrized in terms of eight independent Lorentz-invariant amplitudes, which can then be related to the light-cone GPDs via the quasi-GPDs. The latter are not uniquely defined, and we explore two definitions, one of which is Lorentz invariant. We also discuss the implementation of recent developments in renormalization and $x$-dependence reconstruction. and matching.

Speaker: Prof. Martha Constantinou

Lattice_2026_Constantinou.pdf

14:40 Mellin moments of proton unpolarized GPDs at nonzero skewness from lattice QCD with neural networks

This talk presents an extraction of Mellin moments of the proton unpolarized generalized parton distributions (GPDs) at nonzero skewness from lattice QCD. The analysis builds on the recent studies of GPDs at nonzero skewness, which, together with the polynomiality relations and short-distance factorization matching, connect the moments to generalized form factors. The present method uses artificial neural networks to parameterize the generalized form factors as functions of the invariant momentum transfer and to determine them from lattice data.

Speaker: Manuel Colaço (Adam Mickiewicz University)

gpd_mellin_moments_Manuel_Colaco_lattice.pdf

15:00 Lattice calculation of Generalized Parton Distribution with large-logarithm resummation at non-zero skewness

Large-momentum effective theory (LaMET) allows for a direct calculation of $x$-dependent generalized parton distributions (GPDs) with skewness value $\xi$ on the Euclidean lattice. Large logarithms become present in the lightcone matching process as the momentum fraction of the studied parton approaches 1. We demonstrate a method of resummation for such logarithms as well as provisional results for an application to real lattice data.

Speaker: Jack Holligan

Holligan_Lattice_26.pdf

15:20 The nucleon unpolarized generalized form factors and Mellin moments up to fourth order

Nucleon Mellin moments of parton distribution functions and generalized parton distributions are computed up to the fourth order in lattice QCD. The computation is performed using one ensemble of twisted mass fermions at the physical pion mass point. We employ boosted frames to access the higher-order Mellin moments of generalized parton distributions. We also extract the generalized formfactors up to fourth order. These results establish benchmarks for future lattice studies and expand the understanding of the partonic structure of the proton.

Speaker: Christian Kummer

Lattice2026.pdf

14:00 → 15:40 Theoretical developments and applications beyond the SM

Convener: Evan Berkowitz (University of the Virgin Islands)

14:00 The Neutron Electric Dipole Moment from Lattice QCD using a Background Electric Field

In this talk, I will present recent progress in our lattice QCD calculation of the $\theta$-induced neutron electric dipole moment (nEDM) using the background electric field method. The signal for the nEDM can be enhanced by employing the Feynman–Hellmann theorem. I will also compare results obtained with different nucleon interpolating operators and discuss their effectiveness in suppressing excited-state contamination and improving the signal quality.

Speaker: Fangcheng He

Lattice2026.pdf

14:20 Axial form factor and neutron EDM from lattice QCD

Results on axial vector form factors and contributions of CP violating interactions to neutron electric dipole moment from ongoing calculations by the PNDME and NME collaboration will be presented.

Speaker: Rajan Gupta

Gupta_Lattice_2026.pdf

14:40 Lattice determination of the topological rate at finite momentum in SU(3) Yang-Mills

We present a first lattice study of the momentum-dependent real-time topological transition rate in quenched QCD. In full QCD, this quantity plays an important role in determining the hot axion abundance. The rate is obtained by reconstructing the relevant spectral function from Euclidean topological charge density correlators using the Hansen–Lupo–Tantalo (HLT) method. We present results from simulations of the Wilson gauge action up to $N_\tau=16$, and discuss the extrapolations required to control the continuum, zero-smoothing, and zero-smearing limits. The employed volumes provide access to momenta as large as $p/T\sim 8$.

Speaker: Roberto Dionisio (University of Pisa, INFN sez. di Pisa)

topo_rate_finite_p

15:00 Topological susceptibility in the 2d $O(3)$ nonlinear sigma model using the tree-level improved gradient flow

The two-dimensional $O(3)$ nonlinear sigma model is a well known toy model for studying non-perturbative phenomena in quantum field theory and QCD. With the latter it shares the fact that there is a non-trivial topological structure and the path integral splits into topological sectors. In the lattice theory topology can be defined as well, but semi-classical arguments suggest that the susceptibility $\chi_t$ does not exhibit the correct continuum scaling. Previously, even when using the gradient flow, this scaling could not be found. We provide results for the dimensionless combination $\chi_t \xi^2$ at large correlation lengths $\xi$ and flowtime $t$ for the standard and tree-level Symanzik improved actions and operators, including a first calculation using the tree-level improved gradient flow. We explicitly quantify finite-volume effects and flow-time discretization errors.

Speaker: Mika Lauk (HU-Berlin)

mika_lauk_lat26.pdf

15:20 $\chi$SB for lattice QED in a strong external magnetic field -- $eB$ dependence of the chiral condensate

We use RHMC simulations to study chiral symmetry breaking for massless lattice QED in a strong external magnetic field. Our earlier simulations had shown that chiral symmetry is broken by a strong external magnetic field $B$ with $eB=2\pi\times100/36^2=0.4848...$ at bare coupling $\alpha=1/5$ and predicted the condensate in the massless limit. We had later performed simulations with a relatively weaker external magnetic field $eB=2\pi\times24/36^2=0.1163...$ and the same bare coupling. While we again saw evidence that chiral symmetry was broken in the massless limit, it would have required lattices much larger than we could handle to estimate the value of chiral condensate in this limit. We are now simulating using an intermediate value of the external magnetic field $eB=2\pi\times64/36^2=0.3102...$, and preliminary results indicate that the massless chiral condensate does indeed scale as $(eB)^{3/2}$ as expected.

Speaker: Donald Sinclair (Argonne National Laboratory)

15:40 → 16:10 Coffee break

16:10 → 17:30 Algorithms and artificial intelligence

Convener: James Osborn

16:10 Overcoming Topological Freezing with Multilevel Generative Plaquette Sampling

We propose a multilevel generative sampling framework for lattice gauge theories designed to overcome topological freezing by explicitly sampling all relevant topological sectors. The target distribution is decomposed into coarse and fine scales using an RG-inspired blocking strategy. At each level, the generative sampler produces plaquette degrees of freedom and reconstructs consistent gauge-link configurations through gauge fixing. A mixture-model architecture, together with deterministic sector-changing transformations, enables efficient transitions between distinct winding-number sectors, avoiding the severe critical slowing down typically encountered in HMC. In numerical tests for the two-dimensional U(1) gauge theory, the method achieves good effective sample sizes covering all relevant topological sectors, and accurately reproduces the topological susceptibility.

Speaker: Ankur Singha (Technical University Berlin)

Topological_sectors_in_2D_U_1_-3.pdf

16:30 Optimal Paths through Distribution Space for Mitigating Topological Freezing

Efficient sampling across topological sectors is one of the central algorithmic challenges in lattice field theory. Approaches based on interpolating distributions, such as parallel tempering with defects and learned-flow methods, improve ergodicity by connecting an easily sampled reference system to the target theory, but their efficiency depends strongly on the choice of interpolation path. We study this optimization problem using two complementary approaches. We first show that Fisher information geometry identifies optimal annealing schedules as geodesics in the space of probability distributions. We then introduce a machine-learning framework that searches directly for efficient interpolation paths while allowing both bulk and defect couplings to vary freely. We present results for the CP$^{N-1}$ model, illustrating how optimized protocols improve generalized tempering strategies and provide a systematic route toward mitigating topological freezing.

Speaker: Roberto Dionisio (University of Pisa, INFN sez. di Pisa)

optimal_annealing

16:50 Parallel tempered Metadynamics in full QCD

As the continuum limit is approached, conventional update algorithms in lattice QCD and other topologically non-trivial theories suffer from a particularly severe form of critical slowing down, caused by high action barriers separating distinct topological sectors. Parallel tempered Metadynamics (PT-MetaD) has been shown to overcome this problem by pairing, in the simplest case, the physical simulation with one auxiliary parallel simulation stream in which a bias potential enhances the weight of inter-sector configurations, enabling topological tunneling. Parallel tempering exchanges between the two streams then allow observables to be measured on the unbiased replica, circumventing the reweighting problem that afflicts standard Metadynamics.

In this talk we present several algorithmic advances within, but not limited to, the PT-MetaD framework and provide the first proof-of-concept demonstration in full QCD with dynamical fermions. We further discuss the current status of an ongoing study in high-temperature QCD.

Speaker: Gianluca Fuwa (Bergische Universität Wuppertal)

Lattice2026_Fuwa.pdf

17:10 Exploration of Parallel Tempering on Boundary Conditions

In Lattice QCD, standard Markov Chain Monte Carlo (MCMC) algorithms exhibit topological freezing: As the continuum limit is approached, the autocorrelation times of topological observables increase exponentially. As a result, ergodicity is effectively lost and statistical error estimates become unreliable. A method to mitigate this is Parallel Tempering on Boundary Conditions (PTBC). The algorithm introduces multiple Markov chains: one samples the target distribution and the rest sample modified distributions with progressively shorter autocorrelation times for topological observables. The chains are evolved in parallel using standard MCMC methods, periodically proposing swaps between neighboring chains, enabling configurations to diffuse toward the target chain, satisfying ergodicity. In this talk, we present a study of the different components of the algorithm and their impact on topological observables in SU(3) pure gauge theory.

Speaker: Victor Granados-Pinto (Universität Bern)

16:10 → 17:30 Hadronic and nuclear spectrum and interactions

Convener: Felipe Ortega Gama (UC Berkeley)

16:10 The Electromagnetic Form Factor of the Pion at Large $Q^2$

The accurate determination of the electromagnetic form factor of the pion ($F_\pi (Q^2)$) is of direct phenomenological relevance for upcoming experiments and understanding the transition between non-perturbative and perturbative QCD. Calculations of $F_\pi (Q^2)$ using Lattice QCD have traditionally presented significant challenges. We present new calculations from the QCDSF collaboration of $F_\pi(Q^2)$ up to $Q^2 = 12 GeV^2$ using the Feynman-Hellman theorem in conjunction with momentum smearing, all-mode averaging and variational methods. By computing the pion and kaon form factors for a variety of light and strange masses along the line of constant average SU(3) quark mass, flavour breaking effects are investigated at fixed $Q^2$.

Speaker: Ian Van Schalkwyk

2026_LFT_Talk.pdf

16:30 A calculation of the time-like pion form factor via an infinite-volume approach

In this work we present the first determination of the time-like isovector two-pion form factor from Lattice QCD from an infinite-volume approach based on inverse-problem techniques. Starting from a three-point correlation function involving the vector current and two temporally displaced pion interpolating operators, we reconstruct the spectral density related to the $\gamma\to\pi\pi$ scattering amplitude. We extract the $I=1$ phase shift together with the real and imaginary parts of the form factor from two (Domain-Wall) ensembles at the physical pion mass but with different spatial volumes. By confronting our results with phenomenological estimates and, in the elastic regime, with the traditional finite-volume approach, we validate this methodology which can be extended to the inelastic region.

Speaker: Mr Gabriele Morandi (Università degli Studi di Milano - Bicocca)

Morandi_Lattice-2026.pdf

16:50 Multi-ensemble analysis of rho resonance

We determine the physical pole position of the $\rho$ resonance in $\pi\pi$ scattering using four gauge-field ensembles with 2+1 dynamical quark flavors implemented with a clover improved Wilson action. The ensembles have pion masses $m_\pi = 317,\ 296,\ 174,\ 291$ MeV and lattice spacings $a = 0.114,\ 0.090,\ 0.088,\ 0.068$ fm. For each ensemble, we obtain the $\pi\pi$ energy spectra for multiple total momenta and irreps using the GEVP. We then perform a global fit of the spectra from all ensembles to obtain the scattering amplitude and resonance parameters in the physical limit. This involves parametrizing the quark-mass dependence of the K matrix, solving the finite-volume quantization conditions, and modeling discretization effects in the energy levels. Our analysis will also enable extrapolations of semileptonic transition form factors to the physical point.

Speaker: Luka Jevsenak (University of Ljubljana, Faculty of Mathematics and Physics)

lattice2026.pdf

17:10 Finite temporal size effects on hadronic resonances using lattice QCD

In this talk, we present a finite-volume scattering formalism to study temporal size effects on hadronic resonances using lattice QCD. We use the concept of thermoparticles to derive a finite-temporal size two-particle quantization condition which relates scattering amplitudes to two-particle energies computed in a finite spatial and temporal volume.

Speaker: Jakob Hoffmann (Goethe University, Frankfurt)

Hoffmann_Lattice_2026.pdf

16:10 → 17:30 Quantum computing and quantum information

Convener: Tommaso Rainaldi (Stony Brook University)

16:10 Simulating Lattice Gauge Theories with Virtual Rishons

Classical tensor networks and hybrid quantum-classical algorithms offer a promising path toward simulating the real-time dynamics of lattice gauge theories. In this talk, we present a novel framework that strictly enforces gauge symmetry via a virtual quantum-link rishon representation. Crucially, both gauge and matter degrees of freedom are treated as dynamical variables encoded directly into qubits, enabling the scalable analysis of gauge theories in $d+1$ spacetime dimensions.
We demonstrate the robustness of this framework through classical benchmarks using DMRG in $U(1)$ gauge theories. For $d=1$, we analyze the multi-flavor Schwinger model ($1 \le N_f \le 3$) under arbitrary boundary conditions and a nonzero topological angle, successfully capturing signatures of the underlying Wess-Zumino-Witten conformal field theory. For $d=2$, we showcase its higher-dimensional viability by extracting the confining string tension in close agreement with continuum expectations. Finally, we discuss the outlook for deploying this virtual rishon approach on near-term quantum hardware.

Speaker: David Rogerson (Rutgers University)

David_Rogerson_Lattice_2026_Simulation_with_Virtual_Rishons.pdf

16:30 Quantum Simulations of Lattice QCD in the Representation Basis

In this talk, I present a Hamiltonian for lattice SU($N_c$) gauge theory with staggered and Wilson fermions. A theta angle is also included as part of either a pure-gauge term or a complex fermion mass. The physical, gauge-invariant Hilbert space is formulated in a representation basis, where gauge and fermionic degrees of freedom can be encoded by irreducible representations of SU($N_c$) that tensor at each lattice site to contain a singlet. Small-scale, real-time classical simulations of lattice QCD with Trotterization are performed.

Speaker: Luis Hidalgo

LatticeTalk.pptx

16:50 Quantum Simulation of Gluon Spin-Orbit Correlations in Single- and Multi-Gluon Systems

Gluons in unpolarized hadrons exhibit nontrivial spin-orbit correlations, which at sufficiently small longitudinal momentum fractions, can be characterized by highly entangled quantum states. In this work, we develop a quantum simulation framework to study the coupling between the intrinsic helicity and orbital angular momentum of a gluon on a quantum computer. We extend our framework to simulate the dynamics of multi-gluon systems by incorporating inter-gluon spin-orbit interactions and entanglement, thereby exploring the quantum information structure of gluonic matter on the quantum computer.

Speaker: Juan Antonio Gil Fraile

Quantum Simulation of Gluon Spin-Orbit Correlations in Single- and Multi-Gluon Systems.pdf

Quantum Simulation of Gluon Spin-Orbit Correlations in Single- and Multi-Gluon Systems.pptx

16:10 → 17:30 Quark and lepton flavor physics

Convener: Davide Giusti

16:10 Aspects of a high-precision DWF physics program

I will discuss several aspects of the RBC/UKQCD high-precision DWF physics program including the generation of new gauge ensembles with 2+1 and 2+1+1 flavors up to cutoffs of a^{-1}=11 GeV, dynamical QCD+QED simulations with local vector currents and chiral symmetry, and an improvement to our distillation program. I will give an outlook of the impact of these developments for the g-2 and heavy quark physics program.

Speaker: Christoph Lehner (Universität Regensburg)

lehner.pdf

16:30 Towards the next continuum limit of $\varepsilon'$: Non-perturbative renormalization and contraction software optimization

We present the strategy for non-perturbative renormalization of $K\to\pi\pi$ decay matrix elements in the next continuum limit calculation of direct CP violation parameter $\varepsilon'$ using the RBC/UKQCD collaboration's 2+1 flavor physical point Iwasaki ensembles, with inverse lattice spacings 1.73 GeV (48I) and 2.36 GeV (64I). The new NPR program relies on ten ensembles with half of the lattice spacing of 48I, and eight with half of the lattice spacing of 64I, with the final goal being the computation of the continuum limit of the step scaling function to produce the Z-factor matrix at a much higher scale than allowed by discretization errors on the physical point ensembles. Along with 3-flavor SU(3) symmetric ensembles for both lattice spacings, we include 3+1 flavor ensembles with the same lattice spacing. We also add ensembles that vary the mass of the dynamical light, strange, and charm quark to investigate mass dependence, and one additional 3-flavor ensemble with a fixed global topology. Further, we present progress on the development of GPU accelerated All-to-all correlation functions, and present the speed gained in the various kernels for the calculation of the $K\to\pi\pi$ correlation functions on the 64I ensemble.

Speaker: Jonas Hildebrand (University of Connecticut)

Lattice2026_Hildebrand

16:50 Recent progress on $K\to\pi\pi$ calculation on multiple lattice ensembles

The resent status of RBC/UKQCD's long-time project on $K\to\pi\pi$ decay will be presented. A central focus of this talk will be a study of possible systematic effects in interpolating finite-volume matrix elements, computed for the ground and first excited two-pion states obtained with periodic boundary conditions, to the physical kinematics. As a sensitive diagnostic of this interpolation procedure, we examine the matrix element of the pseudoscalar density $\bar s\gamma_5 d$, which should vanish for on-shell transitions by the equations of motion. We also compare multiple prescriptions for determining subtraction coefficients associated with $1/a^2$ power-divergent mixings and discuss their impact on the interpolated on-shell matrix elements. We then present our first attempt at the continuum limit using a series of coarser lattice ensembles (1.0 GeV and 1.4 GeV) and estimates of the associated systematic uncertainties. Finally, we will report the current status of calculations on a newer series of ensembles with smaller lattice spacings, including first results from the $48^3\times96$ ensemble, as a step toward reducing continuum-extrapolation uncertainties in future determinations.

Speaker: Masaaki Tomii

Lat26_tomii.pdf

17:10 Calculation of Isospin Breaking Corrections to the HVP from RBC/UKQCD

In the current determination of the muon g-2, the hadronic vacuum polarization (HVP) contribution⸺which dominates the theoretical uncertainty⸺is evaluated as an average of different lattice QCD calculations. Since lattice simulations are mostly carried out in isospin symmetric QCD, corrections due to the mass difference of the up and down quarks (strong IB) and the coupling to photons (QED corrections) have to be taken into account. These isospin breaking (IB) corrections are one of the major sources of uncertainty.

I present the current calculation of the IB corrections to the HVP contribution at physical pion mass for the RBC/UKQCD collaborations. We employ the RM123 approach using stochastic coordinate sampling of the all-to-all propagator to evaluate the QED corrections in the QED_L prescription, where also including tadpole contributions. For the connected strong isospin breaking corrections, we compute mass derivatives of the leading connected contribution using multiple different valence quark masses. We determine the shift of the up, down and strange quark masses, by fixing the mass of the neutral pion and kaon and the kaon mass splitting.

Speaker: Julian Parrino (University of Regensburg)

lattice2026_Parrino.pdf

16:10 → 17:30 Software development and machines

Convener: Gunnar Bali (Universität Regensburg)

16:10 Use QUDA with Python

We developed PyQUDA, a Python wrapper for QUDA written in Cython, designed to facilitate lattice QCD calculations using the Python programming language. PyQUDA leverages the optimized linear algebra capabilities of NumPy/CuPy/PyTorch, along with the highly optimized lattice QCD operations provided by QUDA to accelerate research. This integration simplifies the process of writing calculation codes, enabling researchers to build more complex Python packages like EasyDistillation for specific physics objectives. PyQUDA supports a range of lattice QCD operations, including hybrid Monte Carlo (HMC) with N-flavor clover/HISQ fermions and inversion for the Wilson/clover/HISQ fermion action with the multigrid solver. It also includes utility functions for reading lattice QCD data stored in Chroma, MILC, and χQCD formats. Type hints are supported by stub files and multi-GPU support is provided through mpi4py.

Speaker: Xiangyu Jiang (Indiana University)

PyQUDA_Lattice2026.pdf

16:30 Accelerating the HMC in openQxD using QUDA

We present recent developments in the openQxD code, developed by the RC* collaboration. We focus on first steps towards offloading parts of the HMC algorithm using the recently completed interface of our code to the solvers implemented in the QUDA library. As a first high-impact step, the inversions necessary for the pseudo fermion force are offloaded. We provide a breakdown of the time spent in the most computationally intensive kernels within an HMC trajectory and the transfer of data between host and device on the Grace Hopper architecture available at the CSCS Alps system. This is part of a long-term plan to off-load multiple parts of the algorithm to the GPU while staying close to the original structure of the program.

Speaker: Justus Kuhlmann (ETH Zürich)

LATTICE__2026_software.pdf

16:50 Efficient Storage and Compression of Intermediate Data in Lattice Calculations

We present a data-storage and compression tool for managing the large expressions generated in lattice perturbative calculations. A similar strategy may also be applied to numerical nonperturbative data, and this extension is planned for a future version of the tool. In perturbative calculations involving stout-smeared links and improved lattice actions, intermediate expressions may contain millions of terms and are often reused across different stages of the calculation. The tool is implemented as a Mathematica package that provides a uniform interface for native storage and compressed cache files. This storage strategy enables efficient reuse of intermediate results, reduces redundant symbolic computation, and improves the reproducibility and manageability of large-scale lattice perturbative workflows. The compression tools are intended as a practical contribution to the computational infrastructure of lattice field theory, where storage, transfer, and repeated reuse of symbolic and numerical outputs are becoming increasingly important. Our experimental evaluation shows that native storage provides substantial practical gains compared with raw Mathematica source: the stored artifact is approximately 5.2 times smaller, reloads about 25 times faster, and requires about 16.2 times less peak memory during reload.

Speaker: Constantinos Costa (Rinnoco Ltd)

costa_lattice_2026.pdf

17:10 opbasis: automated construction of minimal operator bases for lattice QCD

Constructing minimal operator bases with prescribed transformation properties under discrete symmetries is a recurring task in lattice QCD. Examples include lattice artifacts of local operator insertions, such as the axial vector current, or the construction of interpolating fields with given quantum numbers. The Python package opbasis automates this derivation, with common lattice symmetries built in.

While originally targeted at Symanzik and related continuum EFTs with reduced lattice symmetry, the package has recently been extended to handle irreducible representations of discrete groups such as hypercubic lattice symmetry or boosted variants.

The package is available at https://github.com/nikolai-husung/opbasis.

Speaker: Nikolai Husung (CERN)

example.zip

slides_Husung.pdf

16:10 → 17:30 Structure of hadrons and nuclei

Convener: Yong Zhao

16:10 Pion and Kaon Unpolarized Mellin Moments from Nonlocal Operators

In recent years, methods such as large momentum effective theory (LaMET) and short distance factorization (SDF) have allowed us to extract the $x$-dependence of parton distribution functions (PDFs) utilizing non-local operators of a boosted hadron. Contained within the PDFs is information on fundamental hadronic properties, such as the fraction of the hadron momentum carried by quarks, which is stored in the Mellin moments. By utilizing SDF, we can extract these moments, which are then used as a benchmark of the validity of the PDF reconstructions. The pion is particularly interesting to study as it is the lightest hadron, and its SU(3) symmetry counterpart, the kaon, is also of interest. In studying both of these hadrons, we can compare the up and strange quark contributions individually, study SU(3) symmetry breaking, as well as PDF reconstruction. In this work, we extract the moments at NLO and NNLO accuracy, as well as utilize DGLAP evolution to study systematics associated with perturbative matching. We utilize an $N_f$ = 2+1+1 ensemble of twisted mass fermions with a clover improvement at a pion mass of 260 MeV.

Speaker: Joshua Miller

Lattice_2026_Miller_final.pdf

16:30 Pion and kaon quark GPDs via LaMET and SDF

We present a calculation of the $x$ dependence of unpolarized quark GPDs for the pion and kaon on an $N_f=2+1+1$ ensemble of maximally twisted-mass fermions with a clover term, with lattice volume $32^3\times64$, lattice spacing $a=0.0934$ fm, and pion mass $m_\pi=260$ MeV. The matrix elements contain boosted hadrons coupled to nonlocal operators and are computed for momentum boosts up to 2 GeV and momentum-transfer square up to about 2.5 GeV$^2$. The data are analyzed using both the large-momentum effective theory and short-distance factorization frameworks, providing complementary information. We investigate the dependence of the results on the hadron momentum, momentum transfer, and reconstruction procedure.

Speaker: Joseph Torsiello (Temple University)

Pion and kaon quark GPDs via LaMET and SDF 2 (2).pdf

Pion and kaon quark GPDs via LaMET and SDF 2 (2).pptx

16:50 Moments of pion and kaon light-cone distribution amplitudes from dynamical lattice QCD using the heavy-quark operator product expansion

The light-cone distribution amplitude (LCDA) is a non-perturbative quantity for understanding hadron structure and exclusive scattering processes. We present our calculation of moments of the pion and kaon LCDAs using the heavy-quark operator product expansion (HOPE) framework. This method employs an OPE analysis of hadronic amplitudes through the inclusion of a fictitious valence heavy quark.

Our previous work has successfully applied this framework to determine the second and fourth Mellin moments of the pion LCDA in the quenched approximation. In this work, we extend the application of HOPE to dynamical lattice QCD calculations using CLS ensembles. We present preliminary results for the first three nontrivial Mellin moments of the kaon LCDA and the second moment of the pion LCDA. These results demonstrate the feasibility of the HOPE method for accessing higher moments of meson LCDAs from dynamical lattice QCD.

Speaker: S.-P. Alex Chang (Institute of Physics, National Yang Ming Chiao Tung University)

HOPE_lattice26.pdf

17:10 Tensor-polarised structure functions of the rho meson from lattice QCD using the Feynman–Hellmann method

Spin-1 deep-inelastic scattering targets admit four tensor-polarised structure functions $b_1$–$b_4$ in addition to those of spin-1/2 systems. We present a theoretical framework for the extraction of the tensor-polarised structure functions of general spin-1 systems from the Compton amplitude calculated using the Feynman–Hellmann method, while accounting for the contamination from certain lighter states. The Feynman–Hellmann method relates the energy shift of momentum-projected target correlators under a vector-current perturbation to the forward Compton amplitude, from which the low moments of the structure functions are extracted via the dispersion relations dictated by crossing symmetry. We report lattice QCD calculations of the tensor structure functions of the $\rho$ meson, where there is a theoretical expectation that $b_1 \sim F_1$, and present a pathway for other spin-1 targets.

Speaker: Nabil Humphrey

Lattice_2026_Presentation_NH_FINAL.pdf

16:10 → 17:30 Theoretical developments and applications beyond the SM

Convener: Yannick Meurice (University of Iowa)

16:10 A Vector-Vector-Axial Anomaly in 4D

Because it offers exactly-integer topological quantities, the modified Villain discretization offers a route to correct anomaly structure at finite lattice spacing. I will present a 4-dimensional purely-bosonic modified Villain model with an ABJ-type vector-vector-axial anomaly.

The model appears to have a direct continuous phase transition from one SSB phase to another, giving hope of discovering a 4D CFT with a VVA anomaly.

Speaker: Evan Berkowitz (University of the Virgin Islands)

berkowitz-no-intersections.pdf

16:30 From Lattice to Boundary: Symmetries and Anomalies of 3+1D Staggered Fermions

We investigate the mass term structure and anomalies of the 3+1-dimensional staggered fermion Hamiltonian. We show that the lattice Hamiltonian possesses conserved charges generating the Onsager algebra, which realize $\mathrm{U}(1)_{F_i} \subset \mathrm{SU}(2)_L \times \mathrm{SU}(2)_R$ $(i = x, y, z)$ in the continuum limit. We classify all bilinear mass terms local within a unit cube and clarify the symmetries preserved by each, showing that no mixed 't Hooft anomaly exists between $\mathrm{U}(1)_V$ and $\mathrm{U}(1)_{F_i}$. We further show that introducing a kink profile of the $x$-direction one-link mass --- which preserves the largest residual symmetry among all mass terms --- gaps the 3+1D bulk and localizes two-flavor massless Dirac fermions on the 2+1D domain wall. The bulk Onsager-algebra charges act on the wall as generators of a flavor $\mathrm{SU}(2)$ symmetry, whose associated parity anomaly forbids any symmetric mass gap on the boundary. This shows that the boundary flavor symmetry and its anomaly are not emergent but descend from the ultraviolet lattice Hamiltonian.

Speaker: Tatsuya Yamaoka (The university of Osaka)

V4-2026Lattice.pdf

16:50 Chiral gauge theories on a disk and a slab

The Standard model as a chiral gauge theory is the core foundation of particle physics. Yet, no consensus has been reached on non-perturbative formulations of chiral gauge theories although a few number of promising theoretical models have been constructed. In this work, we exam the extra dimension or domain wall fermion approach. Firstly, we numerically tested the slab (Grabowska-Kaplan) proposal in 2+1 dimensional lattice with a background gauge field and showed anomaly inflow, anomaly cancellation, and the behaviour of the boundary chiral model under different flow of the gauge field. Secondly, we tested a recently proposed proposal with a disk shape defect with a $ S_1 × T_1 $ boundary under annealing flow of the background gauge field. Similarly, we demonstrate the mechanism of anomaly inflow and anomaly cancellation. This work is in collaboration of Rohith Karur and Srimoyee Sen.

Speaker: Jinlong Dang (Peking University)

17:10 Lattice chiral gauge symmetry via bosonization

A central challenge in formulating chiral gauge theories on the lattice is to realize the anomaly-cancellation mechanism of the continuum theory at finite lattice spacing. In this talk, I present a bosonization-based lattice formulation for two-dimensional non-Abelian chiral gauge theories.

In the continuum bosonized description, the gauge anomaly of chiral fermions is encoded as anomaly inflow from a three-dimensional Chern–Simons-type bulk contribution in the gauged Wess–Zumino–Witten model. To obtain a bosonized action suitable for lattice regularization, I introduce gauge-neutral ``spectator fermions''. Motivated by this continuum structure, I construct a lattice counterpart of the gauged Wess–Zumino–Witten model with a three-dimensional bulk extension.

The main result is that the left and right bulk contributions cancel in the exponentiated lattice action when the anomaly-free condition is satisfied, namely when the left- and right-handed representations have matching quadratic indices. This cancellation holds at finite lattice spacing, before taking the continuum limit.

This talk is based on arXiv:2606.12358.

Speaker: Soma Onoda (Kyushu University)

Tuesday 28 July

09:00 → 10:30 Plenary session

Convener: Seyong Kim (Unknown)

09:00 Exploring QCD at finite temperature and density

The lattice-QCD exploration of the QCD phase diagram has advanced considerably in recent years through increasingly precise calculations of thermodynamic observables and fluctuations of conserved charges.
These developments have improved our understanding of strongly interacting matter at finite temperature and density and provided new insights into the QCD transition region.
This overview summarizes recent progress in lattice-QCD studies of the phase diagram, with emphasis on finite-density thermodynamics, fluctuations and correlations of conserved charges, and deconfinement observables.

Speaker: Jana N. Guenther (University of Wuppertal)

Exploring_the_Phase_Diagram_with_Lattice_QCD_preliminary.pdf

09:45 AI/ML for Lattice

I review recent advancements in machine learning and artificial intelligence for lattice field theory, with emphasis on flow-based methods and their applications, as well as agentic AI.

Speaker: Daniel Hackett

10:30 → 11:00 Coffee break

11:00 → 12:30 Plenary session

Convener: Prof. Thomas Luu (Forshungszentrum Jülich)

11:00 Neural Network Ground States for Lattice Gauge Theories

In this talk I will give an introduction to neural network quantum states: a flexible, gauge-symmetry-aware, approach to find the ground state wavefunction of Abelian and non-Abelian lattice gauge theories. I will introduce this method in the context of spin systems, where it was first developed, briefly touching upon some of the applications in condensed matter and quantum chemistry, before covering the works combining this with gauge theories: $Z_2$, $U(1)$, and $SU(2)$. There is an increasing amount of attention paid to tensor network and digital quantum simulation approaches to the Hamiltonian formulation of lattice gauge theories, due in part to the possible access to time evolution and non-equilibrium phenomena. Neural network quantum states, which are also set in this formalism, offer this route to previously hard to access regimes whilst building upon much of the machinery of conventional lattice QCD that has been developed over the past few decades. I will end my talk by drawing attention to the many open-sourced resources in this field, with hopes to lowering the barrier for entry and spark interest in this emerging research area.

Speaker: Thomas Spriggs (QuTech and Delft University of Technology)

11:30 The fate of $U(1)_A$ symmetry in finite temperature QCD

The $U(1)_A$ symmetry is explicitly broken by the axial anomaly, but it may be effectively restored at finite temperature. Over the years lattice QCD studies presented contradictory evidence as to whether this restoration occurs near the chiral transition temperature. In this talk I will review recent theoretical and numerical developments on the fate of $U(1)_A$ in hot QCD, including results that point to restoration well above the chiral transition. I will present the current status of the field and discuss the open questions that remain.

Speaker: Antonio Smecca (INFN - Sezione di Roma Tre)

12:00 The Life and Legacy of Robert L. Sugar

Robert Louis Sugar, known to his friends and colleagues as Bob, played a major role in lattice field theory and, more generally, in theoretical physics. He developed algorithms for condensed matter problems and lattice QCD. He was one of the four founders of the Institute of Theoretical Physics at Santa Barbara funded by National Science Foundation, now known as the Kavli Institute of Theoretical Physics or KITP. Bob was the leader of the MILC Collaboration, and a founder of USQCD. He was the initial chair of the Executive Committee (EC), serving for 8 years, and remaining on the EC for a total of 17 years. Finally, Bob was mentor and friend to many in this community. He was a modest man who truly lived up to his name.

Speaker: Steven Gottlieb (Indiana University)

12:30 → 14:00 Lunch break

14:00 → 15:40 Algorithms and artificial intelligence

Convener: Prof. Shailesh Chandrasekharan (Duke University)

14:00 Generalized Dynamics for HMC

We present a generalization of the dynamics used in HMC that allows for an arbitrary range of auxiliary field content along with freedom in choosing the dynamics (including non-symplectic dynamics), constrained mainly by the Metropolis-Hastings acceptance requirement. We will discuss how the generalized dynamics relates to other HMC variations that have appeared in the literature. We will also explore one variation related to heatbath sampling and present numerical results from 1d XY and 2d U(1) pure gauge theories. Lastly we will mention a few other variations for exploration among the large range of possibilities.

Speaker: James Osborn

14:20 Studying the impact of multiple, localized, gauge-fixed subvolumes with coherent conjugate momenta on the Hybrid Monte Carlo

In this talk we study the impact of altering the standard Hybrid Monte Carlo in numerous small subvolumes of a larger lattice. A primary alteration considered is to fix each subvolume to a maximal tree gauge, such as axial gauge, and then choose conjugate momenta that are not site-local in the subvolume, but rather have spatial coherence acress the subvolume. We focus on pure SU(3) gauge theory and explore whether the choice of non-local conjugate momenta can lead to faster phase-space evolution within the subvolumes and the lattice as a whole.

Speaker: Robert Mawhinney (Columbia University)

14:40 Worldvolume Hybrid Monte Carlo method for lattice gauge theories

The Worldvolume Hybrid Monte Carlo (WV-HMC) method is designed to address the numerical sign problem while avoiding the ergodicity issues inherent in the Lefschetz thimble method. Using a general prescription for applying WV-HMC to group manifolds, I demonstrate its successful application to lattice gauge theories with complex actions.

Speaker: Masafumi Fukuma (Kyoto University)

15:00 Crafting the change of variables for HMC

We explore how a change of variables impacts HMC sampling in lattice gauge theories. Using a 2D U(1) pure gauge system as a testbed, we introduce a local change of variables while keeping the computational cost of the Jacobian low. We analyze how different formulations affect the effective action and the effective force, comparing them to existing field transformation techniques in the literature. We show the scaling behavior of the HMC sampling for the 2D U(1) pure gauge system and discuss the extensibility of this approach to 4D SU(3).

Speaker: Xiao-Yong Jin

15:20 Event-Chain Monte Carlo for pure gauge lattice QCD

Based on https://arxiv.org/abs/2606.21217, we present two adaptations of the Event-Chain Monte Carlo algorithm for pure gauge lattice QCD. The algorithms rely on continuous deterministic updates interrupted by stochastic events, creating an irreversible, rejection-free Markov process that satisfies global balance. We detail the construction of these algorithms and present numerical results on the evolution of autocorrelation times of observables towards the continuum limit. In particular we address whether this alternative class of algorithms can mitigate the critical slowing down of the topological charge.

Speaker: Yacob OZDALKIRAN (IJCLab, Orsay)

14:00 → 15:40 Hadronic and nuclear spectrum and interactions

Convener: Luchang Jin (Univeristy of Connecticut)

14:00 Reconstructing spectral densities from integral transforms I

Spectral densities encode key QCD observables, including hadronic decay rates, cross sections, and transport properties of the quark-gluon plasma. Their Laplace transform corresponds to Euclidean correlation functions, which can be accessed non-perturbatively from first-principles lattice QCD. In this talk, we present analytic formulae to carry out the inverse Laplace transform so as to extract spectral densities from either the continuum or the discrete sampling of correlation functions in the Euclidean time. We first define the spectral observable, possibly regulated and/or smeared, in terms of continuum integral transforms. We then discuss proper modifications for the case where correlation functions are available on a discrete lattice, and explicitly show that the proposed lattice solution tends to its continuum counterpart up to $O(a^2)$ effects if the lattice correlator is $O(a)$-improved.

Speaker: Matteo Saccardi (Colorado State University)

msaccardi_spectral_integrals.pdf

14:20 Reconstructing spectral densities from integral transforms II

Spectral densities encode key QCD observables, including hadronic decay rates, cross sections, and transport properties of the quark-gluon plasma. Their Laplace transform corresponds to Euclidean correlation functions, which can be accessed non-perturbatively from first-principles lattice QCD. Building on our formalism describing how spectral functions can be reconstructed from integral transforms, in this talk we discuss how the lack of knowledge due to a finite temporal extent of the lattice imposes to introduce incomplete integral transforms and the corresponding incomplete smeared spectral densities. We then show how to rigorously bind the contribution from the unknowns so as to estimate and keep under control the associated systematic error, both for the continuous and discrete scenarios. Finally, we present preliminary numerical results where this strategy is applied on vector correlation function obtained from multi-level simulations.

Speaker: Diego Toniolo (University of Milan-Bicocca)

14:40 Spectral reconstruction for reduced excited-state contamination in Euclidean correlators

We present a strategy, based on spectral reconstruction techniques, to extract ground-state energies of Euclidean correlators from smeared observables. The reconstruction acts as a filter on the higher-lying spectrum, suppressing excited-state contamination with respect to the original correlator. The residual contamination is controlled by the smearing hyperparameters, providing an alternative and parameterization-independent way to extract ground-state energies. The approach is illustrated using single-baryon correlation functions at $m_\pi\approx280\,{\rm MeV}$ produced by the Baryon Scattering Collaboration (BaSc).

Speaker: Davide Laudicina (Ruhr Universität Bochum)

15:00 Finite-volume corrections to smeared spectral densities

We present a general framework for quantifying finite-volume effects on smeared spectral densities and apply the result both formally and numerically to the vector-vector channel. Using two independent approaches — finite-volume corrections to Euclidean two-point functions and the Lellouch-Lüscher-Meyer formalism — we show that the leading dependence on the box size is exponentially suppressed and can be written universally in terms of the pion form factor, with both frameworks yielding an equivalent expression. We illustrate the consequences and the utility of the result with numerical estimates based on various smearing kernels and models of particle interactions.

Speaker: Francesca Argia Bresciani (University of Milano-Bicocca)

15:20 Systematic uncertainties in spectral reconstruction from lattice correlators

Reconstructing spectral densities from lattice correlators requires an inverse Laplace transform, which is inherently ill-conditioned. Although there are many approaches to tackle this problem, systematic errors need to be carefully examined. In this talk, we propose a method with a singular value decomposition of the Laplace kernel, in which systematic error can be bounded under reasonable assumptions.

Speaker: Ryutaro Tsuji (KEK)

14:00 → 15:40 Quantum computing and quantum information

Convener: Raghav G. Jha

14:00 Lattice Field theories with Tensor Networks

Tensor networks offer a sign-problem-free framework for studying lattice field theories, provide direct access to partition functions, free energies, and correlation functions through controlled, deterministic approximations. This introductory talk aims to bridge the gap for the lattice community by presenting the essential concepts and computational tools of the tensor network approach.
I will begin with a pedagogical introduction to tensor networks and the role of entanglement in their efficiency. I will then show how the Euclidean path integral of a lattice model maps exactly onto a tensor network: by locally factorising the Boltzmann weights, the partition function becomes the contraction of a translationally invariant network of local tensors, illustrated with both spin models and gauge theories.

Finally, I will survey methods for evaluating these networks, focusing on coarse-graining methods refereed to as Tensor Network Renormalisation, and the challenges of reaching higher dimensions and continuous gauge groups.

Speaker: Adwait Naravane (Ghent university)

14:20 Gauge-invariant PEPS for pure Z_2 gauge theory and its entanglement

We investigate the entanglement structure of the 2+1-dimensional Z_2 lattice gauge theory using tensor-network methods. We construct gauge-invariant ground state based on the gauged Gaussian PEPS (GGPEPS) ansatz proposed by Zohar et al., which automatically satisfies Gauss’ law. This ansatz enables us to study the theory over a wide range of coupling constants while keeping gauge invariance manifest.
By combining the GGPEPS framework with Grassmann tensor network techniques, we perform accurate numerical calculations of physical observables and entanglement properties.

Speaker: Etsuko Itou

14:40 Wavelet Matrix Product States for Quantum Fields

In this talk, I introduce a variational method to solve continuum quantum models with discrete tensor network techniques. The method leverages wavelet matrix product states (wMPS): matrix product states built on top of sufficiently regular ($N\geq 6$) Daubechies scaling functions. These states live in the continuum field theory Fock space, have finite energy density, and can be optimized with standard algorithms, without restriction to free theories. Further, exploiting the multi-resolution analysis built into wavelets, and its quantum circuit description, one can iteratively refine wMPS to obtain accurate approximations at arbitrarily fine length-scales. I showcase the efficiency of the method on the Lieb-Liniger model, computing energy density and correlation functions. This talk is based on arXiv:2606.23823.

Speaker: Molly Kaplan (Inria/Mines Paris - PSL)

15:00 Analyzing the entanglement property of Clifford-circuits augmented MPS

Clifford circuit is a special type of quantum circuit that can generate entanglement states while remaining easily simulable on classical computers. Recently, Clifford-circuits augmented MPS (CAMPS) has been proposed, which consists of the Clifford circuit and matrix product state (MPS). The CAMPS can describe strongly entangled states with smaller bond dimensions than the ordinary MPS. In this work, we implement the CAMPS version of the density-matrix renormalization group (DMRG) algorithm as a library applicable to general spin-1/2 systems. We test the performance of the algorithm in various spin models and confirm that the Clifford circuit reduces the entanglement entropy of MPS. The Clifford circuit automatically obtained by the algorithm describes a nontrivial unitary transformation into a dual model, such as a unitary analogue of the Kramers-Wannier duality. We also discuss potential applications to gauge theories, not only in 1+1 but also in 2+1 dimensions.

Speaker: Akira Matsumoto (Graduate School of Science, Osaka Metropolitan University)

15:20 Fermionic relativistic continuous matrix product states: musings on the Schwinger model

Variational methods based on tensor networks have recently emerged as powerful non-perturbative tools for studying low-dimensional quantum field theories. Relativistic continuous matrix product states (RCMPS) allow certain 1+1 dimensional relativistic quantum field theories to be solved directly in the continuum and thermodynamic limits, without ultraviolet or infrared cutoff.

In this talk I will review the RCMPS approach and present our efforts to extend the formalism to fermionic theories, with the Schwinger model as the target. A central role is played by a set of regularity conditions that the ansatz must satisfy, which constrain the variational parameters and render the variational manifold non-trivial. I will discuss the construction of fermionic RCMPS, how to incorporate the (confining) Coulomb interaction, and our progress towards computing physical observables of the Schwinger model.

Speaker: Sophie Mutzel (Mines Paris, ENS Paris, Inria Paris)

14:00 → 15:40 Quark and lepton flavor physics

Convener: Prof. Stefan Meinel (University of Arizona)

14:00 Determination of SU(3) Chiral Perturbation Theory LECs from $N_f = 2 +1 +1$ HISQ Ensembles

We review the status of a new analysis by the Fermilab Lattice and MILC collaborations towards a correlated determination of SU(3) Chiral Perturbation Theory (ChPT) low-energy constants (LECs). The analysis is based on chiral-continuum fits to light-meson mass and decay constant data generated using highly improved staggered quarks (HISQ) on the $N_f=2+1+1$ MILC HISQ ensembles. Our fitting strategy combines staggered ChPT (SChPT) at NLO with continuum ChPT at NNLO. Since SU(3) ChPT converges poorly at the physical strange quark mass, we restrict this study to ensembles with lighter-than-physical strange quark masses, spanning three lattice spacings. We will discuss the potential of our fits to determine the different LO and NLO ChPT LECs, as well as the strategy to estimate systematic errors.

Speaker: Ramón Merino (Universidad de Granada)

14:20 Kaon semileptonic form factor using $N_f=2+1+1$ PACS10$_c$ configurations

We present a calculation of the form factors for the kaon semileptonic decay process using the $N_f=2+1+1$ PACS10$_c$ configurations. These configurations are generated with the Iwasaki gauge action and the $N_f=2+1+1$ stout-smeared nonperturbatively $O(a)$ improved Wilson quark action at the three lattice spacings, 0.08, 0.06, and 0.04 fm. The spatial volume of the configurations is larger than (10 fm)$^3$ and the masses for the light, strange, and charm quarks are tuned to be close to their physical values. Using our data, we discuss the momentum transfer interpolation and the continuum extrapolation for the form factors. Our preliminary value of $|V_{us}|$ is estimated in the continuum limit, and compared with our previous $N_f = 2+1$ result, those from other lattice groups, and the value obtained from the kaon leptonic decay process.

Speaker: Takeshi Yamazaki (University of Tsukuba)

14:40 Radiative decay of the Kaon into four leptons

We illustrate the results of our recent study of the rare kaon decay $K^{-}\to \ell'^{+}\ell'^{-}\ell^{-}\bar{\nu}_{\ell}$, known as $K_{\ell2\ell'}$ , based on Twisted-Clover simulations at the physical point carried out by ETM collaboration.

The $K_{\ell2\ell'}$ form factors, which have been recently submitted to arXiv:2605.22742, are extrapolated to the continuum limit using three lattice spacings, and the finite volume corrections are investigated using three different volumes. Emission of the photon from the sea is taken into account, and HLT-based methods are used to carry out the needed analytic continuation to Minkowskian spacetime.

The form factors are used to estimate the various lepton channel decay rates within the Standard Model, and to compare it with the existing experimental measurements, as presented in our recent arXiv:2605.22727

Speaker: Francesco Sanfilippo (INFN Roma Tre)

15:00 Four flavors of MDWF

I will describe our new lattice action using Möbius Domain Wall Fermions (MDWFs). The gauge action is tree-level Symanzik-improved with a rectangle coefficient of $c_1=-1/12$ and bare coupling $\beta$. The four flavors of MDWF utilize a Dirac operator with 8 iterations of Stout link smearing with $\rho=1/8$, which is comparable to gradient-flow smearing radius of 1 in lattice units. A domain-wall height of $M_5=1.0$ is used for all $\beta$ and $L_5$ and the $b$ and $c$ Möbius parameters are tuned to keep $m_{\rm res} \lesssim1.5$ MeV on all ensembles. With a modest allocation on Perlmutter at NERSC, we have generated more than 30 ensembles spanning $135\lesssim m_\pi\lesssim460$ MeV and $0.05\lesssim a\lesssim0.12$ fm. Details of the HMC integrator, topological charge, gradient flow scales, autocorrelation times and other details will be provided. The configurations used in arXiv:2605.06560 are publicly available via globus as described in the preprint.

Speaker: Andre Walker-Loud (Lawrence Berkeley National Laboratory)

15:20 $F_{K}/F_{\pi}$ and $F_{D_{s}}/F_{D}$ from four flavor Möbius Domain Wall Fermions

We present a determination for the ratio of light and D meson decay constants in lattice QCD. This work employs a new four flavor Möbius Domain Wall fermion action with 30 ensembles across five lattice-spacings, multiple volumes, and a range of pion mass down to the physical point. In this talk we will discuss our calculation and extrapolation analyses, giving $F_{K^{\pm}}/F_{\pi^{\pm}}$ = 1.1962(34), along with preliminary results for $F_{D_s}/F_{D}$ which are both key inputs for precision tests of CKM unitarity.

Speaker: Zack Hall (Lawrence Berkeley National Laboratory)

14:00 → 15:40 Standard-Model parameters

Convener: Andrea Shindler

14:00 Gradient flow renormalization for composite fermion operators

We present a practical gradient-flow (GF) renormalization scheme for composite fermion operators based on conserved-current correlation functions. The method determines the fermion wave-function renormalization nonperturbatively from simple two-point correlators, avoiding the need for calculating local flowed operators. The resulting GF-renormalized operators are finite at nonzero flow time and can be matched to the $\overline{\mathrm{MS}}$ scheme through known short flow-time expansion (SFTX) coefficients.

As an application, we present a nonperturbative determination of the mass anomalous dimension and the corresponding flow-time evolution operator that connects the lattice and $\overline{\mathrm{MS}}$ schemes. Combining the nonperturbative results with perturbative SFTX predictions for $\gamma_m$ significantly reduces the residual flow-time dependence of renormalized observables, leading to a more reliable matching to the $\overline{\mathrm{MS}}$ scheme at short flow time.

Speaker: Anna Hasenfratz

14:20 Renormalized quark masses from gradient flow using HISQ ensembles

Renormalized quark masses are fundamental parameters of the Standard Model, serving as critical inputs for theoretical predictions across a wide range of physics processes. In this work, we study Highly Improved Staggered Quark (HISQ) ensembles in the gradient flow lattice scheme. Using a small subset of our physical point ensembles, we compute flow-time-dependent renormalized quark masses using two methods. The first method is inspired by the Partially Conserved Axial Current (PCAC) relation, and the second method determines the mass renormalization factor. We then match the gradient flow quark masses to the $\overline{\mathrm{MS}}$ scheme. Our preliminary results provide guidance on the optimal flow and operator definitions for our upcoming production runs.

Speaker: Mingwei Dai (University of Illinois Urbana-Champaign)

14:40 Determination of the strong coupling from gradient flow

The strong coupling $\alpha_{\mathrm{s}}(m_{Z})$ at the pole mass $m_{Z}$ of the $Z$ boson is a fundamental parameter of the Standard Model. I discuss ongoing efforts targeting a precise determination of the strong coupling from the continuous (infinite volume) gradient flow $\beta$-function using the highly improved staggered quark (HISQ) action.

Speaker: Curtis Peterson (Michigan State University)

15:00 Update on hadronic $D$ decays at the SU(3) flavour symmetric point

We report on recent progress in extracting multi-hadron $D$ decay amplitudes in a pilot study using three ensembles of stabilised Wilson fermions at the SU(3) flavour-symmetric point. Our focus is on the analogue of $D \to K\pi$, where the final state is in the flavour 27-plet. The calculation involves two key steps: determining the finite-volume spectrum for five total spatial momenta in a variational analysis and extracting the relevant finite-volume weak matrix elements from lattice three-point functions. We summarise the challenges and progress of the ongoing calculation, including continuum extrapolation strategies for finite-volume energies across the three ensembles and for S-wave scattering parameters. We also discuss the extraction of finite-volume matrix elements of four-quark weak Hamiltonian operators that describe $D$-meson transitions to two-hadron final states. This is achieved using optimal final-state operators constructed from the scattering analysis. Finally, we provide an initial indication of the signal that can be achieved once all parts of the calculation are combined, including the Lellouch-Lüscher and renormalisation factors relating the finite-volume matrix elements to the physical amplitudes. The calculation uses exact distillation, implemented in the Grid and Hadrons software libraries.

Speaker: Max Hansen

14:00 → 15:40 Structure of hadrons and nuclei

Convener: Frank Winter (Jefferson Lab)

14:00 Lattice extraction of the Collins-Soper kernel via auxiliary fields

The Collins-Soper kernel is a key, universal quantity that relates transverse momentum dependent distributions (TMDs) at different rapidity scales through an evolution equation. The CS kernel may be obtained through the TMD soft function by formulating the Wilson line in terms of 1-dimensional auxiliary fermion fields on the lattice. The complex auxiliary field directional vectors can be mapped directly to the Wilson line rapidity in Collins' definition of the TMD soft function. We find that our computation can be carried out at high statistical precision, and obtain results with uncertainties that are comparable with state of the art lattice results. Our uncertainties are dominated by the perturbative matching that is necessary for our method. Moreover, we find that the CS kernel has a plateau in the large $b_\perp$ region.

Speaker: Wayne Morris (National Yang Ming Chiao Tung University)

14:20 First constraints on the nonperturbative gluon Collins-Soper kernel

This talk will present the first nonperturbative constraints on the gluon (CS) Collins-Soper kernel — a universal anomalous dimension of transverse-momentum-dependent gluon distributions — in the range of transverse momentum scales $q_{T} \in [300\text{ MeV}, 1.3\text{ GeV}]$. The constraints are obtained with lattice QCD at a close-to-physical pion mass $M_\pi = {172(3)}\text{ MeV}$, a single lattice spacing $a=0.15\text{ fm}$, and next-to-next-to-leading logarithmic matching in Large-Momentum Effective Theory. These results represent the first step toward a controlled determination of the kernel, with eventual impact on phenomenological analyses sensitive to the gluon structure of hadronic matter.

Speaker: Artur Avkhadiev

14:40 Gluon Collins-Soper Kernel with Coulomb-Gauge Operators

We will present preliminary results on a lattice QCD study of the gluon Collins-Soper kernel using Coulomb-gauge gluon operators. This kernel governs the rapidity evolution of transverse-momentum-dependent gluon distributions and is nonperturbative at small transverse momentum. The calculation is performed at near-physical pion mass and shows improved statistical precision with this approach.

Speaker: Yang Fu (MIT)

15:00 Proton TMDPDFs from Lattice QCD Using Domain-Wall Fermions

We present the first lattice-QCD determination of isovector proton transverse-momentum-dependent parton distribution functions (TMDPDFs) simultaneously in the unpolarized, helicity, and transversity channels. The calculation is performed within large-momentum effective theory using Coulomb-gauge-fixed quasi-TMD correlators on a $2+1$-flavor domain-wall fermion ensemble at the physical pion mass with lattice spacing $a=0.0836~{\rm fm}$. We use proton quasi-TMD beam functions at boost momentum $P_z=1.62~{\rm GeV}$, with the transversity channel newly computed here, and extract the Collins-Soper kernel and intrinsic soft function from pion quasi-TMD wave functions with momenta up to $P_z=1.85~{\rm GeV}$ and large-momentum pion form factors with momentum transfer up to $Q^2=13.7~{\rm GeV}^2$, respectively. Using the matching formula with next-to-leading-logarithmic (NLL) resummation, we extract the corresponding light-cone TMDPDFs in the moderate-$x$ region as functions of Bjorken $x$ and transverse separation up to $b_T \gtrsim 1~{\rm fm}$, accessing a nonperturbative region that is weakly constrained by experiment. The unpolarized, helicity, and transversity TMDPDFs exhibit remarkably similar $b_T$ dependence, providing evidence that these three $T$-even leading-twist channels share approximately universal nonperturbative transverse dynamics, with only mild polarization dependence in the explored moderate-$x$ region. The large-$b_T$ behavior is constrained by the ratio-scheme intrinsic soft function and is used to obtain transverse-momentum-space TMDPDFs through Fourier transformation. These results provide a benchmark lattice-QCD prediction for the nonperturbative three-dimensional partonic structure of the proton relevant to future precision TMD phenomenology.

Speaker: Jinchen He (University of Maryland)

Lattice2026-Jinchen.pdf

15:20 Exploring Color Flows in TMDs: Disconnected Wilson Loops on the Lattice

One of the foremost goals of research into Quantum Chromodynamics (QCD) is to quantify the internal structure of the proton from first principles. Ab initio calculations of QCD matrix elements like transverse momentum distributions (TMDs) using lattice QCD are an essential part of achieving that goal. I present first explorations of effects on TMDs induced by the more intricate color flows in hadron-hadron collisions compared to the standard SIDIS and Drell-Yan processes. I analyze the correlations between proton, antiproton, and pion two-point functions with Wilson loops computed in lattice QCD. I consider Wilson loops of various shapes, and find a correlation between the two-point function and Wilson loop insertion which is significant and nonzero for narrow Wilson loops with widths up to 5 lattice spacings (0.57 fm) and for the first two momenta available on the lattice. This disconnected quark contribution will be combined in forthcoming work with connected three-point functions containing non-standard Wilson gauge link structures, to assemble the full modified TMD observables.

Speaker: Jyn Peyton (New Mexico State University)

14:00 → 15:40 Theoretical developments and applications beyond the SM

Convener: Nobuyuki Matsumoto (Boston University)

14:00 Progress on scalar singlets and glueballs in lattice gauge theories coupled to matter fields in multiple representations

We investigate the low-lying flavour-singlet spectrum of an $Sp(4)$ lattice gauge theory with fermions in both the fundamental and two-index antisymmetric representations, using the Wilson gauge action and Wilson fermions. Our analysis employs a generalized eigenvalue problem on a basis of smeared interpolating operators comprising glueball and meson operators from both fermion representations in two large ensembles with the same inverse coupling and similar quark mass parameters. A first determination of the spectrum shows that the lightest flavour-singlet state is a scalar. We observe evidence for meson–glueball mixing. We improve upon previous determinations of the energy eigenstates and mixing angles in the flavour-singlet pseudoscalar sector.

Speaker: Nuno Brito (University of Plymouth)

14:20 Progress on the Sp(4) lattice gauge theory at finite temperature in the presence of fermions

We investigate, for the first time, the Sp(4) lattice gauge theory in the presence of fermions at finite temperature, examining the theory with two dynamical Wilson fermions in the fundamental representation. The continuum theory is of interest as it provides a realisation of composite dark matter and may generate an observable stochastic gravitational wave signal, sourced by a phase transition in the early universe. Evaluating the sensitivity of future gravitational wave experiments to this signal requires knowledge of the strength of the phase transition. We explore the two dimensional parameter space of the theory, defined by the bare fermion mass and inverse gauge coupling. For this exploratory study we focus on lattices with small number of sites in the temporal dimension. We analyse the finite volume scaling behaviour of Polyakov loop observables, specifically the scaling of the peak of the susceptibility, informed by multi histogram reweighting, to discriminate between the presence of a phase transition or crossover. In the light fermion mass regime we find strong indications of a crossover, while in the regime of heavy fermion mass we find preliminary evidence of a first order phase transition. These findings motivate further studies of the continuum limit for this and other gauge groups in the Sp(2N) family.

Speaker: Alexis Harilaos Verney-Provatas (Swansea University/The University of Edinburgh)

14:40 Progress on $Sp(4)$ Gauge Theory with $N _{\rm f}=2$ Fundamental Möbius Domain Wall Fermions

We present an extensive study of Möbius domain wall fermions (MDWF) in four-dimensional $Sp(4)$ gauge theory with two dynamical fermions transforming in the fundamental representation. This is, to our knowledge, the first comprehensive application of MDWF to $Sp(4)$ lattice gauge theories, which are relevant to composite Higgs and dark matter models based on the $SU(4)/Sp(4)$ coset. The MDWF algorithm improves the realisation of the enhanced global symmetry at finite fifth-dimensional extent by applying a Möbius transformation to the Wilson kernel, reducing residual global symmetry breaking at fixed computational cost after suitable tuning. As preparation for large-scale spectroscopy, we scan the residual mass over the bare gauge coupling and the unphysical Möbius-kernel parameters. This identifies regions where the Hermitian Wilson-kernel spectrum lies safely above the mobility edge, limiting the impact of non-localised near-zero modes. Guided by this tuning strategy, future MDWF spectroscopy studies can improve on previous Wilson-fermion measurements and enable continuum-limit extrapolations with reduced lattice discretisation effects.

Speaker: Gianmarco Simonetti (The University of Edinburgh/Swansea University)

15:00 Zeros of the partition function for 12 flavor QCD and the spectral gap

We discuss recent numerical results for the zeros of the partition function for a four dimensional SU(3) lattice gauge theory with 12 staggered fermions having identical masses and an unimproved action (arXiv: 2606.14642).
Our results indicate that beyond some critical mass, a gap between the lowest zero and the real axis in the complex coupling plane develops and can be related to the spectral gap for the 0++ scalar. We comment on related results by Jin and Mawhinney, and more recently Klinger et al. (arXiv:2603.20099).
We report on recent progress regarding the chiral condensate distribution and the possibility of calculating the zeros using Tensor Renormalization Group methods.

Speaker: Yannick Meurice (University of Iowa)

15:20 First Overlap Formulation and Perturbative Results for Supersymmetric QCD

We present a lattice formulation of $\mathcal{N}=1$ supersymmetric QCD (SQCD) based on overlap fermions, providing a discretization consistent with the Ginsparg–Wilson relation. Particular emphasis is placed on the construction of Yukawa terms that preserve a lattice-modified chiral symmetry involving overlap quarks and gluinos. To realize this modified chiral symmetry in the Yukawa sector, we follow Lüscher’s strategy and introduce auxiliary Dirac and Majorana fermionic fields for the quark and gluino fields, respectively. After functional integration over these auxiliary fields, ultralocal interaction terms arise as additional contributions to the lattice action. Within this framework, and using the Wilson gauge action for gluons, we also carry out one-loop perturbative calculations. In particular, we compute the self-energies of the quark, gluon, gluino, and squark fields in the presence of quark and squark masses, enabling an unambiguous determination of the corresponding field and mass counterterms on the lattice. This work provides a robust foundation for future perturbative determinations of the fine-tunings of the gauge, Yukawa, and quartic couplings, and already shows, as expected, a reduction in the number of required counterterms relative to Wilson-type fermions.

Speaker: Dr Marios Costa (Cyprus University of Technology)

Marios_Talk_Lattice2026.pdf

15:40 → 16:10 Coffee break

16:10 → 17:30 Algorithms and artificial intelligence: I

Convener: Masafumi Fukuma (Kyoto University)

16:10 Projected Density Matrix Sampling for Quantum Lattice Hamiltonians

We present a continuous-time path-integral Monte Carlo method for computing the low-lying spectrum of generic quantum lattice Hamiltonians, motivated in part by applications to qubit regularizations of quantum field theories. The method is based on projecting the thermal density matrix, $e^{-\beta H}$, onto a subspace spanned by a chosen set of linearly independent states. It is free of Trotter discretization errors and systematically converges, with increasing $\beta$, to low-energy states that have finite overlap with the projection subspace. While most effective for systems without a sign problem, it can also provide information about low-energy spectra of systems with sign-problems. Some applications are presented to illustrate the method.

Speaker: Prof. Shailesh Chandrasekharan (Duke University)

16:30 Reweighting using the worldline formalism

We propose a hybrid reweighting method to calculate expectation values of observables in the presence of external fields coupled to dynamical fermions. The reweighting factor is calculated from the ratio of fermion determinants with and without the external field, evaluated on a background of Wilson-flowed dynamical gauge fields. Because the Wilson flow greatly reduces ultraviolet fluctuations, this determinant ratio can be efficiently evaluated numerically using the worldline formalism, after applying a Whittaker-Shannon-type interpolation to embed the discrete lattice configurations into continuous space. Under fixed flow times, we can take the lattice continuum limit of the reweighted data along standard continuum trajectories. With the addition of appropriate counterterms and renormalization, physical results are obtained from a smooth extrapolation to the zero-flow-time limit.

As a primary example, we discuss the application of this method to physical systems, particularly QED in non-trivial backgrounds below the Schwinger pair-production threshold.

Speaker: Dr En-Hung Chao (Massachusetts Institute of Technology)

16:50 Efficient Hybrid Monte Carlo for Pfaffian Quantum Monte Carlo

Auxiliary-field quantum Monte Carlo methods provide a powerful route to unbiased simulations of strongly correlated quantum systems. While determinant quantum Monte Carlo has been highly successful, its standard formulation is naturally adapted to particle-number-conserving Hamiltonians. Pfaffian quantum Monte Carlo extends this framework to systems, that do not conserve particle number.

Existing implementations of Pfaffian quantum Monte Carlo have largely followed the BSS approach. In this talk, I will present the construction of an efficient Hybrid Monte Carlo (HMC) formulation of Pfaffian quantum Monte Carlo, bringing the advantages of HMC sampling to a broader class of fermionic systems. The central idea is to adapt the efficient matrix-product routines used in HMC formulations of determinant quantum Monte Carlo to the Pfaffian formulation, while preserving the same computational asymptotic scaling.
Because Pfaffian quantum Monte Carlo is naturally formulated in the Majorana basis, additional Hubbard–Stratonovich decoupling channels become available, which can in some cases alleviate or remove the sign problem. The resulting interactions, however, can be non-diagonal and often lack simple closed-form force terms. I will present a method to circumvent this difficulty by approximating the gradient without introducing any systematic errors into the observables.

Speaker: Thomas Hauschild (Forschungszentrum Juelich)

17:10 H$^2$MC: A Hybrid Hamiltonian Monte Carlo framework for interacting quantum wires

Stochastic methods are indispensable tools for studying strongly correlated fermionic systems due to their far more favorable volume scaling than direct approaches such as exact diagonalization (ED) or tensor network methods. However, this improved scaling comes at the cost of new challenges, most notably the sign problem and long autocorrelation times, which severely restrict the accessible parameter space.

In this talk, we consider a 2D system of interacting quantum wires and show how partially retaining ED in Hamiltonian Monte Carlo (HMC) simulations mitigates these limitations while preserving scaling advantages over full ED. Specifically, we demonstrate that this Hybrid Hamiltonian Monte Carlo framework, dubbed H$^2$MC, significantly alleviates the sign problem and shortens autocorrelation times compared to pure HMC formulations based on real and imaginary Hubbard-Stratonovich transformations. We further show how incorporating pseudofermion analogues into this framework yields additional computational speedups while simultaneously reducing memory requirements.

Together, these results illustrate how combining seemingly disparate numerical methods can overcome limitations that are otherwise intrinsic to each approach individually.

Speaker: Finn Temmen (Forschungszentrum Jülich, IAS-4)

16:10 → 17:30 Algorithms and artificial intelligence: II

Convener: Letizia Parato (University of Colorado - Boulder)

16:10 Tackling the Sign Problem in the Doped Hubbard Model with Normalizing Flows

The Hubbard model at finite chemical potential is a cornerstone for understanding doped correlated systems, but simulations are severely limited by the sign problem. In the auxiliary-field formulation, the spin basis mitigates the sign problem, yet severe ergodicity issues have limited its use. We extend recent advances with normalizing flows at half-filling to finite chemical potential by introducing an annealing scheme enabling ergodic sampling. Compared to state-of-the-art hybrid Monte Carlo in the charge basis, our approach accurately reproduces exact diagonalization results while reducing statistical uncertainties by an order of magnitude, opening a new path for simulations of doped correlated systems.

Speaker: Dominic Schuh (University of Bonn)

16:30 Machine-Learned Density of States for the Doped Hubbard Model

In this work, we extend the normalizing-flow-based generalized density-of-states (NF-gDoS) method to the doped Hubbard model. The Hubbard model is known to exhibit a sign problem in the presence of a chemical potential. The NF-gDoS framework is attractive because it reformulates the original complex-weight sampling problem by separating the complex phase from the Boltzmann distribution and encoding it instead in a one-dimensional oscillatory integral.
Recent studies have demonstrated that the NF-gDoS method can successfully reconstruct the partition function in 1+1D scalar field theory, correctly reproducing the Lee–Yang zeros. In a separate study of 1+1D U(1) gauge theory with a $\theta$-term, it was shown that the density of states can be qualitatively reconstructed, highlighting the importance of expressive normalizing flows.
Building on these results, we apply expressive conditional-normalizing-flow (CNF) architectures to the doped Hubbard model and systematically benchmark the resulting density of states against exact results for small system sizes. Our study provides a first assessment of the applicability of CNF-gDoS to a strongly correlated fermionic system. We identify key challenges, including limitations related to model expressivity and stability, and outline possible directions for improving the robustness of the approach in more demanding regimes.

Speaker: Felicitas Freche

16:50 Generative Models for the Low-Temperature Hubbard Model

Generative modeling of strongly correlated fermionic systems has emerged as a promising complement to traditional quantum Monte Carlo methods. Building on recent demonstrations that normalizing flows can learn the Boltzmann distribution of the Hubbard model, we systematically investigate the path toward larger lattice sizes and lower temperatures. We identify the key challenges that arise in simulating the Hubbard model at scale and propose targeted strategies to address them.

Speaker: Janik Kreit (University of Bonn)

17:10 Low-Temperature Hybrid Monte Carlo for Perylene and Corannulene: Stabilizing Determinant and Force

Our central advance is an algorithm that simultaneously stabilizes the determinant and force calculations that holds to machine precision for very large $\beta$ (in units of inverse hopping) while scaling equally well with standard determinant QMC simulations of these systems. Furthermore, our formalism retains the full time-displaced (2-point) Greens function, allowing us to construct any $n$-body correlator, including those that contain disconnected diagrams. We demonstrate our formalism by presenting large $\beta = 90$ (corresponding to (low) room-temperature) Hubbard-model simulations of the molecules perylene and corannulene at different doping levels, and calculating one-, two- (exciton) and three-body (trion) correlators.

Speaker: Petar Sinilkov (IAS-4, Forschungszentrum Jülich)

16:10 → 17:30 Hadronic and nuclear spectrum and interactions

Convener: Archana Radhakrishnan

16:10 Finite-Volume Effects to Meson Masses in QCD+QED with C* Boundary Conditions

Due to the long-range nature of QED, finite-volume corrections to observables appear as inverse powers of lattice extent, which may be much larger than the exponentially suppressed corrections. For precision computations, it is crucial to determine these effects, which depend on the QED formulation. As a first step, we investigate the power-law finite-volume effects in the QCD+QED setup with C* boundary conditions on pseudoscalar meson masses. We measure the spectrum on four ensembles generated by the RC$*$ collaboration with $L= 1.7-3.5 \,\mathrm{fm}$ and $N_f=1+2+1$ $\mathcal{O}(a)$-improved Wilson fermions. The isospin-breaking effects are added perturbatively to $\mathcal{O}(e^2)$ via the RM123 method. We compare the observations to the expected electromagnetic finite-volume effects in the continuum, which can be expressed in terms of known hadronic amplitudes and form factors.

Speaker: Klemen Kersic (ETH Zürich)

16:30 Finite-Volume Effects to the HVP in QCD with C* Boundary Conditions

Finite-volume effects constitute one of the main sources of systematic uncertainty in lattice determinations of the hadronic vacuum polarization (HVP) contribution to the muon's $g-2$. In this talk, we investigate these effects in a lattice QCD setup with C$^\star$ boundary conditions. We compute the HVP intermediate-window observable on four gauge ensembles generated by the RC$^\star$ collaboration, with identical bare parameters and pion mass $m_\pi \simeq 400$ MeV, but different physical volumes in the range 1.7-3.5 fm. This setup allows for a controlled numerical study of the volume dependence while keeping all other parameters fixed. In addition, we present ongoing work on an extension of the Hansen-Patella method to C$^\star$ boundary conditions, towards a theoretical understanding of the observed finite-volume effects.

Speaker: Paola Tavella (ETH Zürich)

16:50 The pion mass splitting from lattice QCD

We present a lattice QCD calculation of the charged–neutral pion mass splitting at O($\alpha_{\rm em}$) using a coordinate-space photon propagator regulated à la Pauli-Villars (PV). The calculation is performed using CLS ensembles. The elastic contribution receives a dedicated treatment to reduce finite-size effects and speed up the approach to infinite PV cutoff. The same methods are being applied to the kaon mass splitting, which allows for a calibration of the bare up/down quark mass difference.

Speaker: Harvey Byron Meyer (CERN)

17:10 First-principles determination of anomaly-induced pion decay beyond the chiral limit

We report a lattice QCD calculation of the neutral pion decay $\pi^0\to\gamma\gamma$ beyond the chiral limit. We develop a three-point-function strategy, based on an anomalous PCAC relation, to extract the finite-quark-mass corrections to the decay amplitude, including both isospin-symmetric and isospin-breaking effects.

Speaker: Tian Lin (Peking University)

16:10 → 17:30 Quantum computing and quantum information

Convener: Lena Funcke (University of Bonn)

16:10 QFT Thermodynamics from Entanglement Entropy

In this talk, I will present our argument that, in the limit of large subregions, the derivative of entanglement entropy (EE) with respect to the size of the entangling region approaches the thermal entropy density for general QFTs. We provide validation for these claims from our lattice computations in the three-dimensional O(4) model at finite chemical potential by showing that in the corresponding limit, the EE derivative satisfies the same Maxwell relation as the thermal entropy density. These results pave the way for extracting thermodynamics from EE data in general QFTs.

Speaker: Aatu Rajala (University of Helsinki)

16:30 Probing magic and entanglement in 1+1-dimensional SU(2) lattice gauge theory

Magic and entanglement quantify departure of quantum systems from classical world: the former measures the deviation from stabilizer states that can be efficiently simulated classically while the latter measures non-local correlations. A proper understanding of magic in physically relevant quantum field theories is essential for identifying where quantum advantage may be realized in the early fault-tolerant quantum computing era. We calculate the gauge-invariant entanglement entropy and stabilizer Rényi entropy of the ground state of the (1+1)-dimensional SU(2) lattice gauge theory and find a crossover regime where the ground state passes from a more magic-rich regime into a regime with less magic which is also tracked by the sharpest change of both the entanglement entropy and lattice particle density.

Speaker: Dr Raghav G. Jha

16:50 Encoding Entropy and Spatial Entanglement in Hamiltonian Lattice Gauge Theory

Hamiltonian simulations offer a promising path for computing the nonperturbative real-time dynamics of gauge theories. In this setting, entanglement entropy is both a diagnostic of many-body correlations and, together with other resources, relevant to the cost of representing, preparing, and evolving quantum states. Quantum simulations often employ distinct formulations of the same lattice gauge theory, with different tradeoffs between locality and constraint complexity. Although these formulations encode the same gauge-invariant physics, they use different elementary degrees of freedom and hence different tensor-product structures. Consequently, physically equivalent formulations need not assign the same entanglement entropy to the same state. We introduce the encoding entropy, defined by bipartitioning the native tensor factors of a chosen Hamiltonian formulation. This quantity characterizes the correlation structure intrinsic to that encoding, but need not measure spatial correlations when the formulation is spatially nonlocal. To probe the latter, we adopt the Kogut-Susskind extended-Hilbert-space entropy as a fixed reference definition of spatial entanglement. We compute both quantities for several formulations of SU(2) lattice gauge theory in (1+1)D and (2+1)D. In spatially local formulations, the reference spatial entropy can be related to the native variables through local transformations at the boundary of a region. In spatially nonlocal formulations, it is instead recovered through a nonlocal reconstruction of the Kogut-Susskind spatial algebra. Our results distinguish formulation-dependent encoding correlations from spatial correlations and clarify how the latter can be extracted across different Hamiltonian encodings.

Speaker: Navya Gupta

17:10 SOCS: Spins on Curved Surfaces

We study quantum spin systems on curved geometries in one and two spatial dimensions using tensor networks method. We investigate the information scrambling properties as well as thermodynamic behavior of these systems including correlation functions and entropy scaling.

Speaker: Abhishek Samlodia (Syracuse University)

16:10 → 17:30 Quark and lepton flavor physics

Convener: Luka Leskovec (Jozef Stefan Institute & Faculty of Mathematics and Physics, University of Ljubljana)

16:10 Renormalizing the two-photon contribution to $K\to\mu^+\mu^-$ I

We discuss the counter terms needed to renormalize our recent $K\to\mu^+\mu^-$ decay calculation (Phys.Rev.D 113 (2026) 7, 074523). Three different classes of divergent sub-diagrams are identified and the steps needed to renormalize them described. The relation between these classes and the five distinct types of quark contractions is described in terms of an expansion in powers of $\alpha_s$ evaluated at the energy scale of the charm quark mass.

Speaker: Norman Christ (Columbia University)

K2mumu.pdf

16:30 Renormalizing the two-photon contribution to $K\to\mu^+\mu^-$ II

We present strategies for determining the counterterm coefficients required to complete our recent calculation of the long-distance contribution to the $K_{\rm L}\to\mu^+\mu^-$ decay amplitude (Phys. Rev. D 113 (2026) 074523). These counterterms are absent in the more convergent four-flavor calculation because of the Glashow–Iliopoulos–Maiani (GIM) cancellation. This allows the required three-flavor counterterms to be determined by matching to the corresponding four-flavor theory. Since only short-distance quantities are involved in this matching, the four-flavor calculation can be performed economically in a small volume with unphysically heavy quark masses. We have implemented part of the required renormalization procedures and preliminary numerical results for the $K_{\rm L}\to\gamma\gamma$ amplitude, which is rendered UV finite at zeroth order in $\alpha_s(m_c)$, will be presented.

Speaker: Ceran Hu (Columbia University)

16:50 Finite-volume effects to hadronic observables in lattice QCD+QED

At current levels of precision, QED corrections to hadronic observables can no longer be neglected. For a broad class of QED regularizations, these corrections generate power-law finite-volume effects on a finite lattice volume, which are a leading source of systematic uncertainty. We revisit the structure and size of QED finite-volume effects, with particular focus on electroweak decay rates of hadrons.

Speaker: Davide Giusti

17:10 Finite-volume effects in the factorizable contributions to light-meson leptonic decay rates in QCD+QED

Leptonic decay rates are used to extract the elements of the Cabibbo-Kobayashi-Maskawa matrix; reaching sub-per cent precision requires including isospin-breaking effects, i.e., electromagnetic effects and effects from the explicit difference between the up and down quark masses. One of the major sources of systematic error in computing leptonic decay rates in QCD+QED is electromagnetic power-law finite-volume effects, which are expected to be large for a wide class of finite-volume formulations of QED.
In this talk, we present a numerical study of finite-volume effects in the factorizable diagrams for the pion and kaon leptonic decay rates, using ensembles from the BMW Collaboration with N$_{f}=2+1+1$ staggered quarks and stout smearing at the physical pion mass. We focus our study on a single lattice spacing $a=0.1315$ fm and use four spatial extensions ranging from $3.2$ fm to $8.4$ fm.

Speaker: Alessandro Cotellucci (Forschungszentrum Jülich)

16:10 → 17:30 Software development and machines

Convener: Anthony Grebe (University of Maryland, College Park)

16:10 Easier parameter scans with hmcdj

We present hmcdj, a new tool developed to ease the process of generating large numbers of gauge ensembles for a given theory. Building on top of the Grid library, hmcdj allows quick specification of theories in C++ with minimal boilerplate, and precise specification of per-ensemble parameters to be controlled at run time from a YAML input file. Additionally, it supports many quality-of-life features for managing large numbers of running jobs, including automatic tuning of the molecular dynamics step size to control the Metropolis acceptance rate; output of ILDG-compliant binary and metadata; and integration with HPC schedulers to dynamically adapt the target trajectory count of a job to match its time limits. hmcdj is openly available under the GPLv2 license, and welcomes new contributions.

Speaker: Alexis Harilaos Verney-Provatas (Swansea University/The University of Edinburgh)

16:30 AI/ML-inspired RMHMC kernels--CPN model study

Riemannian manifold HMC (RMHMC), following the basic idea of Fourier acceleration, has been studied as a viable algorithm toward mitigating critical slowing down. In fact, by using multilevel integration, the algorithmic overhead becomes additive to the fermionic inversion cost that dominates in production runs, especially with domain-wall fermions. Given the rapid development of AI/ML, we explore constructing the kernel as a neural network. Using the CPN model as a testbed, we report on the results from representative kernels. We further report on software development towards migrating to QCD.

Speaker: Nobuyuki Matsumoto (Boston University)

16:50 AmPyL: A python toolkit for three-particle finite-volume spectra and scattering amplitudes

AmPyL is an open-source Python package for relating finite-volume lattice data to infinite-volume scattering amplitudes, with particular emphasis on three-particle systems. The library provides an object-oriented framework for constructing all aspects of the relativistic-field-theory three-particle formalism, including flavor and spectator channel spaces, finite-volume kinematics, finite-volume irreducible-representation projections, finite-volume matrices, two- and three-body K matrices, and quantization conditions. This talk will introduce the structure of AmPyL, show how it can be used to compute three-particle finite-volume spectra from amplitude parameters, and discuss its role in making multi-hadron amplitude extraction more transparent, reproducible, and accessible.

Speaker: Max Hansen

16:10 → 17:30 Structure of hadrons and nuclei

Convener: Yang Fu (MIT)

16:10 Computing the Gluon Momentum Fraction of Nucleons on the Lattice through the Gradient Flow

We present our recent results for the gluon momentum fraction of the nucleon using lattice quantum chromodynamics (QCD), with a nonperturbative renormalization technique based on the gradient flow. Various techniques are used to reduce statistical and systematic uncertainties. The variational method is used to reduce excited-state contamination. Distillation is employed to reduce the costs arising from a large operator basis. To reduce systematic uncertainties, we apply Bayesian model averaging to all fit procedures. The momentum fraction is computed on gradient-flowed ensembles. We apply matching coefficients to the flow-time dependent lattice results to recover the gluon momentum fraction in the MS-bar scheme at 2 GeV. Our final result is $\langle x \rangle_g(\mu = 2 \; \mathrm{GeV}) = 0.482(35)$ computed at a single lattice spacing and pion mass.

Speaker: Alex Sturzu (William and Mary)

16:30 Gluon Parton Distribution Functions From Boosted Euclidean Correlators in the Coulomb Gauge

Gluon parton distribution functions (PDFs) from large momentum effective theory (LaMET) have remained in poor statistical precision compared to non-singlet PDFs due to their correlators coming solely from disconnected diagrams. One method to improve the long distance signal is to remove the Wilson lines from the correlators, which are present solely to maintain gauge invariance, and compute the new correlators in a gauge fixed calculation. This method has been proven theoretically and numerically in recent quark calculations. The main challenge here is recomputing the perturbative matching for the Coulomb gauge operators. We present our perturbative and numerical results for new Coulomb gauge gluon operators.

Speaker: William Good (Michigan State University)

16:50 Toward the lattice calculation of pion gluon GPD

Gluon generalized parton distributions (GPDs) are important quantities for understanding the three-dimensional structure of hadrons. They encode information about the spatial distribution of gluons, as well as the mass and spin structure of hadrons, and provide access to the gluon contribution to orbital angular momentum, which is at the heart of the proton spin puzzle. In this talk, I will present initial progress toward a lattice-QCD calculation of gluon PDF and GPD of the pion. Gluon-related hadron structure observables have notoriously large statistical uncertainty. I will show preliminary results for unrenormalized pion PDF and GPD matrix elements, including both forward and off-forward cases, and examine gluon matrix elements relevant to the tensor decomposition of gluon GPD. These linear combinations provide the lattice input needed for the extraction of gluon GPDs. These matrix elements will be the starting point for further analysis, including renormalization, and matching to light-cone distributions.

Speaker: Sicheng Liu (stony brook)

17:10 Perturbative study of higher-moment operators in the Wilson-flow framework on the lattice

We apply the Wilson-flow framework in lattice perturbation theory to study the renormalization of non-singlet twist-two quark bilinear operators containing up to five covariant derivatives. These operators are relevant for the determination of the first six moments of parton distribution functions. In our analysis, we derive the relevant Feynman rules by solving the lattice gauge and fermion flow equations perturbatively. We then compute the one-loop Feynman diagrams contributing to off-shell amputated Green’s functions of the flowed operators with external quark fields. Based on these results, we examine whether residual finite mixing effects allowed by hypercubic symmetry persist in the Green's functions of flowed operators after taking the continuum limit. Our lattice calculation can be useful for improving systematics in future studies employing flowed operators.

Speaker: Dr Gregoris Spanoudes (University of Cyprus)

16:10 → 17:30 Theoretical developments and applications beyond the SM

Convener: Matteo Bresciani (Trinity College Dublin)

16:10 Domain-wall-seeded bubble nucleation on the lattice

First-order phase transitions are common in many beyond the Standard Model theories. Nucleating transitions are particularly interesting, since they leave behind a gravitational wave background (GWB) that could be observable in many near-future experiments. The nucleation rate determines how fast the transition completes and is needed for precision predictions of the GWB.

Typically, the metastable system is assumed to be spatially homogeneous. In contrast, in the seeded case the nucleation probability is locally enhanced by some impurity in the system, such as a topological defect. We consider a system of two scalar fields in two dimensions with a domain wall as the impurity. The scenario is a two-step transition in which the first transition leaves behind a system of domain walls that in turn seed the second transition to the true vacuum.

For suppressed transitions the rate is estimated using Markov chain Monte Carlo to determine the statistical probability of critical bubbles. For faster nucleation, as in our case, we can simply evolve the system in time and wait for the nucleation to occur. We compare the simulation results to analytic estimates computed in an effective field theory living on the domain wall and find good agreement.

Speaker: Jaakko Hällfors

16:30 The Physics of Phase Transitions is Universal, Numerical Simulations aren't

The 3D chiral Heisenberg model is a theory of relativistic fermions in three spacetime dimensions with SU(2) symmetry. We simulate it numerically as a lattice field theory using domain wall fermions and locate the phase transition corresponding to spontaneous SU(2)$\to$U(1) breaking. This phase transition belongs to the large "chiral Heisenberg" universality class, containing among others the semi-metal - Mott insulator transition of the (2+1)D Hubbard model on the honeycomb lattice. Our simulation results are considerably removed from estimates obtained from simulations performed in (2+1)D, but align more closely with analytic estimates obtained using 3D covariant field theory. The tension between the two approaches is evident, but it is unclear what exactly is causing this discrepancy and, more importantly, how it can be eliminated in the future. We encourage the community to contemplate this apparent limitation of numerical simulations. We also present first results for the anti-symmetric matrix-valued fermion correlator which turns out to be technically very challenging to analyse.

Speaker: Johann Ostmeyer (University of Bonn)

16:50 Order-Order Interface Tension in SU(N) Gauge Theory

In pure SU(N) gauge theory, we measure interface tensions between distinct deconfined phases (different $Z_N$-centers) using two complementary methods. These deconfined-deconfined (DD) interface tensions generally depend on the $Z_N$-phase shift across the interface and on the temperature T. We use a twisted boundary condition to produce two ordered phases simultaneously with a DD interface naturally lying between them. In the first method, we evaluate the surface tension by calculating the difference in free energy of the twisted and non-twisted lattices, employing multicanonical sampling to accurately measure the first-order phase transition region. In the second, we extend the mixed phase / capillary wave method previously applied to determine the interface tension of the confined-deconfined (CD) interface in pure SU(N > 3) gauge theory, to measure the DD interface. With these methods, we map the $T$-dependence of the different DD interface tensions in SU(4) and SU(8) to see whether they show Casimir scaling for $T \gg T_c$ and whether there is perfect wetting in the limit $T \rightarrow T_c$.

Speaker: Aaron Haarti (University of Helsinki)

17:10 Magnetic Phase Transitions in Zigzag Graphene Nanoribbons at Finite Chemical Potential: Mean-Field Theory and Hybrid Monte Carlo

Zigzag graphene nanoribbons are narrow strips of graphene with parallel zigzag edge termination that sparked research interest in recent years due to their distinctive electronic and magnetic properties. They exhibit partially flat edge bands around the Fermi level that host edge-localized states. These edge states give rise to a robust magnetic order. At half-filling, the edges are known to host electrons with opposite spin orientation (AF order). Upon increasing the chemical potential, the magnetic order is reported to transition from the AF order to ferromagnetic inter-edge coupling with the same spin polarization on both edges (F order), and back to the AF order. These transitions can be attributed to the filling of edge bands alone.

We perform self-consistent mean-field theory calculations to determine the magnetic order of the ground state at various chemical potentials and ribbon widths. In particular, when we tune the chemical potential to align with higher energy subbands, referred to as bulk bands, we predict additional magnetic order phase transitions in sufficiently wide zigzag ribbons. Their appearance is linked to an interplay between the spectral overlap of edge and bulk bands and the fact that the AF order bands are spin-degenerate while the F order bands split into two spin subbands.

At half-filling, we perform Hybrid Monte Carlo (HMC) simulations to go beyond mean-field calculations. Work is underway in an attempt to verify the self-consistent theory results at finite chemical potential, focusing on narrow ribbons and moderate chemical potential, where the first AF-to-F order phase transition is expected to occur.

Speaker: Felix Strohkirch

Wednesday 29 July

09:00 → 10:40 Algorithms and artificial intelligence

Convener: Matteo Saccardi (Colorado State University)

09:00 Operator Learning for spectral reconstruction in lattice QCD

Spectral reconstruction is one of the most challenging and important problems in lattice QCD, as spectral functions are directly related to a wide range of phenomenologically relevant observables. In this talk, I present a novel strategy based on reformulating the reconstruction problem within the framework of Operator Learning using DeepONet neural networks. The network is trained in a supervised way, and I introduce an effective approach to generating training datasets that incorporates prior knowledge without relying on a predefined family of parametric models. I also show how systematic uncertainties can be reliably quantified within the machine-learning framework and validate the method on previously unseen mock data. As a benchmark on true lattice data, I reconstruct the inclusive decay rate in the 1+1-dimensional $O(3)$ non-linear $\sigma$ model, recovering the analytical result with high precision. This approach has the potential to improve the precision of the calculation of spectral-density-related observables compared with established non-machine-learning reconstruction methods.

Speaker: Alessandro De Santis (Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz)

09:20 Direct and indirect inverse-Laplace strategies for spectral reconstruction

Reconstructing spectral information from Euclidean lattice correlators is a central inverse problem in lattice QCD. The correlator is related to the underlying spectrum through a Laplace-type transform, but inverting this relation from finite and noisy data is severely ill-conditioned. In this contribution, we discuss two complementary strategies for approaching this problem. The first attempts to recover spectral information by numerically inverting the Laplace relation itself. The second avoids a full inversion and instead extracts spectral information through a parametrized or smeared representation of the correlator, such as a finite set of exponential contributions or localized spectral structures. Using mock lattice-like correlators, including noisy data and near-degenerate spectral contributions, we compare the behavior of these strategies across several algorithmic workflows. The comparison illustrates the different roles of direct inversion, regularized reconstruction, and parametrized spectral extraction in lattice-QCD spectroscopy.

Speaker: Demetrianos Gavriel

09:40 Spectral density reconstruction from lattice QCD correlators: an approach via numerical anti-Laplace transform. Numerical treatment.

Euclidean lattice correlators can be written as Laplace transforms of given spectral functions. Solving for the latter would thus simply amount to computing anti-transforms, which is unfortunately the prototype of an ill-posed problem. If one numerically approximates the integral transform via (e.g.) Gauss-Laguerre quadratures, the inverse problems is turned into a linear system, which is, not surprisingly, ill-conditioned, and thus asks for regularization. Our choice is a Tikhonov prescription. Once regularized, the system is manageable: most interestingly, given a value for the Tikhonov regulator, the anti-transform of an exponential decay is a given function, which turns out to be a legitimate regularization of a Dirac delta function. In this way, according to our prescription, the (numerical) inverse Laplace transform of a correlator can be fitted versus the superposition of transformed exponential templates. The method turns out to be successful, opening the way to multiple applications in lattice QCD. We present both the strategy of our approach and the numerics which go on top of it, discussing tests on mock (and actual) correlators, and stability of the method when applied to noisy signals.

Speaker: Francesco Di Renzo

10:00 Spectral density reconstruction from lattice QCD correlators: an approach via numerical anti-Laplace transform. Analytical characterisation

We will discuss the analytical characterisation of the Laplace transform inversion problem turned into a finite-dimensional linear system. This is done via a Gauss-Laguerre quadrature rule and regularised by means of a Tikhonov prescription. This, in the light of solutions obtained by, e.g., M. Hansen, et al. & M. Saccardi et al. via the implementation of other methods/regulation prescriptions will help gain understanding of the underlying connection granted by the singular value decomposition of the equivalent statements of the inverse problem when applied to lattice correlators. We show that all solutions for our problem when applied to sums of exponentials will be a superposition of a certain regularization of the Dirac delta. This allows us to devise several spectral reconstruction strategies based on minimization of a particular lagrangian 'cost' function

Speaker: Jose Alejandro Vidal Maxia (University of Parma & INFN)

10:20 Optimized solver algorithms for computing $Tr(A^{-1})$

Estimating the trace of the inverse of a large quark matrix is a longstanding problem in lattice QCD. Hutchinson's method is the standard for this calculation, which uses random noise vectors to achieve a desired tolerance. Doing so requires solving a system of linear equations $Ax = b$, where $b$ is the random noise vector. In this work, we introduce novel solving algorithms for use in Hutchinson's method: Non-symmetric Lanczos, Twin BiCG, and Twin BiCGStab. On the whole, these algorithms benefit from fewer matrix vector products per iteration and are very naturally adapted to large-scale GPU and other distributed HPC environments. These algorithms are tested on variable size lattice QCD matrices and in various computing contexts. The first part of this talk will highlight the solver methods and interpret testing results. The second part of this talk will discuss how these methods stand in service of a more sophisticated evaluation of $Tr(A^{-1})$ which implements a polynomial approximation of $A^{-1}$ and a singular value deflation.

Speaker: Benjamin Luke (Baylor University)

09:00 → 10:40 Hadronic and nuclear spectrum and interactions: I

Convener: Patrick Oare (Brookhaven National Laboratory)

09:00 Feynman-Hellmann method for four-quark matrix elements

Neutrinoless double beta decay ($0\nu\beta\beta$) is the most promising low-energy probe of physics beyond the Standard Model (BSM). If experimental searches which are underway detect such decays, understanding which BSM theory best fits the data will require theoretical work to disentangle Standard Model contributions to the process from experimental measurements. The only known way to determine QCD contributions to the process is with lattice methods. While methods exist to calculate long-range contributions to the process without placing full nucleons on the lattice, no method has yet been demonstrated which can overcome the signal-to-noise problem for heavy-physics contact interactions between nucleons. We explore a Feynman-Hellmann (FH) method adapted for four-quark matrix elements. FH methods have previously been used to boost the signal for nuclear matrix elements with bilinear currents. Naive calculation of the summed sequential two block propagators necessary for the method are at present computationally intractable at lattice sizes which approach the physical limit. We investigate four-quark matrix elements on small lattice sizes in order to determine whether further development is justified to optimize the necessary calculations for FH at adequate sizes.

Speaker: Charles Kacir (University of North Carolina at Chapel Hill)

09:20 Resolving vector-current spectral functions with singular value decomposition

We study vector current correlators using the singular value decomposition (SVD) of the Laplace kernel, $\exp(-\omega\tau)$, which identifies the components of the spectral function that can be reliably reconstructed from Euclidean correlator data. The vector-current correlator provides access to the spectrum of interacting two-pion states, including the $\rho$-resonance region. We test the method using mock data constructed from the Omnès representation of the timelike pion form factor, as well as simulated lattice correlators. We then investigate how sensitively the SVD-projected observables constrain model parameters of the spectrum.

Speaker: Sakura Itatani (SOKENDAI / KEK)

09:40 Improving the Wilson action

A very popular choice for the fermion action used in lattice computations is the well-known $\mathcal{O}(a)$-improved Wilson action, which has been successfully employed in a wide range of applications. However, experience with this action has also revealed some of its limitations, such as the presence of small and even negative eigenvalues of the lattice Dirac operator due to the breaking of chiral symmetry, and discretization effects that have been observed to be larger than those of other actions for some quantities. In this talk, I will discuss some modifications to the action aimed at addressing these issues, namely the use of smearing, an exponentiated clover term, and the inclusion of a dimension-six operator to remove $\mathcal{O}(a^2)$ effects at tree level. I will also show how each of these modifications individually contributes to reducing discretization effects and the breaking of chiral symmetry.

Speaker: Jorge Baeza Ballesteros (DESY Zeuthen)

10:00 Highly improved staggered quarks on anisotropic lattices

The highly improved staggered quark action (HISQ) has been in use for about two decades now in calculations ranging from the hadronic contribution to the anomalous magnetic moment of the muon to QCD thermodynamics. Large data sets have been generated that allow for well-controlled chiral-continuum extrapolations. However, a class of problems that require some form of spectral reconstruction from Euclidean correlation functions, requires anisotropic lattices with a higher resolution in the temporal direction. We report on the project of developing a framework for simulations with anisotropic highly improved staggered quarks (aHISQ). Exploring a range of anisotropies from 1 to 8 on quenched ensembles, we study the dependence of the staggered pion taste mass splittings on anisotropy for the naive staggered and aHISQ action. We discuss an empirical model that captures the main features of the aHISQ spectrum and comment on the observed qualitatively different behavior of the naive and aHISQ taste spectrum with anisotropy.

Speaker: Oleksiy Bazavov (Michigan State University (US))

10:20 Update on the gradient flow scale on CLS ensembles

Within the RQCD collaboration, we are currently updating the determination of the gradient flow scale at the physical point using the $\Xi$ baryon mass as input. We utilize more than 50 CLS ensembles generated with non-perturbatively $O(a)$-improved Wilson dynamical fermions. These ensembles comprise six lattice spacings in the range of $a = 0.04-0.1$ fm, spatial volumes satisfying $L M_\pi > 4$, and pion masses ranging from around 420 MeV down to the physical point. Compared to our previous determination, we have improved the statistics on existing key ensembles and added several new ones. Most notable is a $256 \times 128^3$ lattice at almost physical quark masses with a small lattice spacing of $a \approx 0.05$ fm. Combined quark-mass, continuum-limit, and finite-volume fits are performed on the baryon octet masses along three trajectories in the quark-mass plane. This approach tightly constrains the baryon masses at the physical point. Besides the details on the numerical computation, we also present aspects of data management and provenance.

Speaker: Wolfgang Söldner

latt26.pdf

09:00 → 10:40 Hadronic and nuclear spectrum and interactions: II

Convener: Maxim Mai (University of Bern)

09:00 Finite-volume quantization condition from the N/D representation

We discuss a model-independent method for determining hadronic resonances from lattice QCD, derived from the $N/D$ representation of a partial-wave two-body amplitude. The new formalism is valid for energies coinciding with arbitrary left-hand cuts of the amplitude.

Speaker: Sebastian Dawid (Indiana University Bloomington)

09:20 $NN$ scattering amplitudes at light quark masses

We present a calculation of $NN$ scattering amplitudes in both isospin states, $I = 0$ (deuteron) and $I = 1$ (dineutron), on CLS ensembles with pion masses ranging from 700 MeV down to 200 MeV. A particular focus of our analysis is on the left-hand cut arising from one-pion exchange, which induces effects not accounted for in the usual two-particle finite-volume formalism. We explore two alternatives which are valid in the presence of the left-hand cut: the plane-wave quantization condition and the relativistic left-hand-cut formalism. While the effects of the left-hand cut are suppressed at large pion masses, we find them to be significant at the lower pion masses. We find that the deuteron is a virtual state even at the lowest pion mass considered (200 MeV); however, there is a clear trend of decreasing inverse scattering length with lower quark mass.

Speaker: Miguel Salg (University of Bern)

09:40 From lattice QCD to ab initio nuclear physics via finite-volume pionless EFT

Lattice QCD calculations of many-body nuclear systems are prohibitively expensive due to the signal-to-noise problem. An alternative framework to compute nuclear observables from first principles is to compute few-nucleon quantities and match them directly to pionless EFT to obtain LECs, which can then be used in nuclear many-body methods. This work employs pionless EFT at the physical pion mass, with matching data (two-body scattering lengths, and three-body binding energies) taken from experiment. We optimize wavefunctions of correlated gaussians via gradient-based differential programming at LO in pionless FVEFT, with NLO corrections incorporated perturbatively. Preliminary results indicate broad agreement with binding energies for up to 12 nucleons, demonstrating viability of this approach for larger nuclei.

Speaker: Rosemary Zielinski (Massachusetts Institute of Technology)

10:00 NuLattice: Computations of nuclei on lattices

Computations of nuclei starting from nuclear Hamiltonians have seen significant progress in the past two decades. Such calculations start from interactions from effective field theory. The Hamiltonians are then typically expanded in a harmonic oscillator basis and solved using systematically improvable many-body methods. Calculations on a discrete position-space lattice offer a promising alternative. Nuclear forces are short-ranged, so the resulting Hamiltonians are sparse. I will present progress on computations of nuclei on the lattice using the Python package NuLattice. I will introduce quantum and classical computations using zero-range interactions. I will present computations of nuclei and nuclear matter using simple interactions, benchmarking results from Nuclear Lattice Effective Field Theory for the first time. Many of these Hamiltonians do not give realistic saturation properties, and we investigate the mechanisms that lead to saturation on the lattice.

Speaker: Matthias Heinz

10:20 Nucleon Charges from PNDME and NME Collaboration

Results from ongoing calculations of the "nucleon charges" by the PNDME and NME collaboration are presented. These are based on preliminary data from O(7000) configurations on two physical pion mass ensembles with 2+1+1-flavor ensembles generated by the MILC collaboration at lattice spacing $a=0.087$ and $a=0.0576$ fm and 11 NME ensembles with 2+1-flavor clover action generated by JLab/W\&M/LANL/MIT/Marseille collaborations. Control of excited-state contamination is discussed in the extraction of the axial, scalar, and tensor charges.

Speaker: Jun-Sik Yoo (Los Alamos National Laboratory)

09:00 → 10:40 Quantum computing and quantum information

Convener: Sophie Mutzel (Mines Paris, ENS Paris, Inria Paris)

09:00 Quantum State Initialization: Approximating Hamiltonian Eigenstates by One- and Two-Qubit Gates

Abstract:
One of the key issues in studying quantum many-body systems and quantum field theories is characterizing eigenstates of Hamiltonians. However, the exponential growth of the Hilbert space poses a challenge for classical simulations. Tensor Networks, specifically Matrix Product States (MPS), have emerged as a framework to address this by compactly representing many-body wavefunctions through local tensors connected by a virtual bond. We utilize MPS to initialize quantum devices, which can potentially overcome entanglement barriers of classical computers.

We approximate the ground state of the target Hamiltonian by a variational optimization of an MPS. This MPS is subsequently mapped into a quantum circuit composed of one- and two-qubit gates. Subsequent layers are obtained through a variational procedure using the Hamiltonian transformed by the preceding layers, ensuring a consistent iterative optimization. We investigate the efficacy of this approach on several systems, including the ground states of quantum Ising, XY, and Heisenberg models. Our method guarantees that the variational energy improves with each additional layer, consistently approaching the target ground state energy. Furthermore, an increase in fidelity is observed as the number of layers increases.

Speaker: Yao Ting Su

09:20 Counterdiabatic quantum optimization for gauge theories

The Quantum Approximate Optimization Algorithm (QAOA)[1] is one of the leading variational quantum algorithms used to prepare the ground state of gauge theories. The design of QAOA is under-pinned by the adiabatic theorem. Recently, there has been a proposed variation of QAOA, DC-QAOA[2], that incorporates counterdiabatic driving in order to speed up the adiabatic process, leading to reduced circuit depths and runtimes. In this work, we use QAOA and DC- QAOA, along with other counterdiabatic variations [3, 4], to find the ground state of the Schwinger model and compare the results to show how counterdiabatic driving can be used to improve the ground state preparation of gauge theories.

References:

[1] Edward Farhi, Jeffrey Goldstone, and Sam Gutmann. A quantum approximate optimization algorithm, 2014.

[2] P. Chandarana, N. N. Hegade, K. Paul, F. Albarran-Arriagada, E. Solano, A. del Campo, and Xi Chen. Digitized-counterdiabatic quantum approximate optimization algorithm. Physical Review Research, 4(1), February 2022.

[3] Pranav Chandarana, Narendra N. Hegade, Iraitz Montalban, Enrique Solano, and Xi Chen. Digitized counterdiabatic quantum algorithm for protein folding. Physical Review Applied, 20(1), 2023

[4] Ruoqian Xu, Sebastian V. Romero, Jialiang Tang, Yue Ban, and Xi Chen. Digitized counterdiabatic quantum optimization for bin packing problem. EPJ Quantum Technology, 12(1), August 2025.

Speaker: Ethan Laval (University of Southampton)

09:40 CaRBM: A Fixed-Depth Quantum Algorithm with Partial Correction for Thermal State Preparation

We introduce the CaRBM algorithm for fixed-depth thermal state preparation. Our algorithm is based on thermal state purification and uses the Restricted Boltzmann Machine (RBM) block-encoding scheme to implement the imaginary-time propagator $e^{-\beta H}$, which is implemented in the quantum circuit in a fixed-depth manner via Cartan decomposition. Our algorithm performs best at high temperatures, with the success probability of the block encoding decreasing as the temperature decreases. To increase the success probability, we have devised a correction scheme for the block-encoding that increases the temperature range our algorithm reliably probes. We demonstrate our algorithm by calculating the partition function zeros of the XXZ model and the phase diagram of the Gross-Neveu model, which is a model of strongly interacting relativistic fermions.

Speaker: Omar Alsheikh

10:00 Dissipative State Preparation for Lattice Gauge Theories

Preparing low-energy states of lattice gauge theories (LGT) on quantum computers remains a central challenge. Standard approaches such as adiabatic evolution, variational algorithms, and eigenstate filtering are often limited by large circuit depths, closing gaps, costly classical optimization, or the need for high-overlap initial states. Dissipative state preparation offers an alternative route, where a Lindbladian is engineered so that the target state is its unique fixed point within a chosen symmetry sector. This has the advantage that any initial state in the symmetry sector, even one with zero overlap, can be driven to the target state. In this work, we apply a dissipative algorithm to the $\mathbb{Z}_2$ LGT in $1+1$D as a first testbed. The key step is designing jump operators that preserve the relevant symmetries, including gauge invariance, momentum, and charge conjugation, so that the dynamics remain confined to a chosen sector by construction. Within this framework we target the vacuum as well as meson states at both zero and nonzero momentum. We present preliminary numerical evidence that dissipative methods can successfully obtain these states, which is a first step toward dissipative preparation in richer gauge theories.

Speaker: Hersh Kumar (University of Maryland College Park)

10:20 Quantum data learning of phase transitions

Quantum data learning (QDL) provides a framework for extracting physical insights directly from quantum states. In this presentation we develop QDL techniques for detecting the phase transition in the 2+1-dimensional toric-code loop-gas model in a magnetic field. Our unsupervised QDL approach recovers the phase structure and locates the phase transition with a small offset as expected in finite volumes; both supervised and unsupervised QDL methods outperform classical alternatives. These findings establish QDL as an effective framework for characterizing topological quantum matter, studying finite volume effects, and probing phase diagrams.

Speaker: Tanmoy Bhattacharya (Los Alamos National Laboratory)

09:00 → 10:40 Quark and lepton flavor physics

Convener: Balint Toth (University of Wuppertal)

09:00 Hadronic vacuum polarization contribution to the tau anomalous magnetic moment

We report on an ongoing effort to determine the hadronic vacuum polarization contribution to the anomalous magnetic moment of the tau from lattice QCD. The calculation is based on CLS ensembles with $N_f=2+1$ flavours of $O(a)$-improved Wilson fermions, covering five lattice spacings and a range of pion masses, including the physical point. Because of the short-distance nature of this observable, particular attention is given to the control of cutoff effects and to the continuum extrapolation, together with other sources of systematic uncertainty. We present preliminary results for the leading-order hadronic vacuum polarization contribution to the tau anomalous magnetic moment and discuss the status of the full error budget.

Speaker: Alessandro Conigli

09:20 Beyond the leading-order hadronic vacuum polarization contribution to the muon $g-2$

A detailed understanding of the time kernels entering the time-momentum representation of hadronic vacuum polarization (HVP) observables is a prerequisite for precision lattice determinations of a broad class of quantities. Building on recent analytical developments, we discuss the properties of these kernels and their role in controlling the time integral relevant to HVP observables.

As a first application, we present our complete results for the first high-precision determination of the next-to-leading order HVP contribution to the anomalous magnetic moment of the muon. Using more than 30 independent CLS gauge ensembles with $\mathrm{O}(a)$-improved Wilson fermions, together with window observables and dedicated treatments of several sources of systematic uncertainty, including short-distance cutoff effects and finite-volume corrections, we achieve a final precision better than $0.6\%$.

Finally, we report on ongoing efforts to extend this framework to other low-energy hadronic vacuum polarization observables, including the anomalous magnetic moment of the electron and related quantities, such as the slope of the vacuum polarization function at vanishing momentum. These studies include observables sensitive to the low-momentum structure of the vacuum polarization function, where lattice determinations become increasingly challenging due to long-distance noise.

Speaker: Arnau Beltran (JGU Mainz)

09:40 Isospin-breaking corrections for muon g-2 hadronic vacuum polarization

We give an update on progress by the Fermilab Lattice, HPQCD, and MILC collaborations on computing isospin-breaking corrections for the hadronic vacuum polarization (HVP) contribution to the muon's anomalous magnetic moment. These effects, specifically electromagnetic corrections and strong-isospin breaking (SIB) corrections, are small but important to determine accurately for our sub-percent level, complete lattice calculation of the HVP, as discussed in a companion talk. All calculations are performed on 2+1+1 flavor HISQ ensembles; the forthcoming SIB results will include new results on ensembles with a~0.076 and 0.057fm, as well as improved statistics compared with our previous published results. In addition, we discuss a method for using charge spurion analysis to analyze the chiral dependence of electromagnetic effects.

Speaker: Ethan Neil

10:00 Toward a complete sub-percent lattice determination of the muon g-2: Update from Fermilab Lattice, HPQCD and MILC

Toward a complete sub-percent lattice determination of the muon g-2

We present an update on the Fermilab Lattice, HPQCD, and MILC collaboration's ongoing effort to compute the leading- and next-to-leading-order hadronic vacuum polarization (HVP) contributions to the muon anomalous magnetic moment. We report preliminary results for the long-distance disconnected and I=0 contributions obtained using a new dataset at a lattice spacing of 0.057 fm. We also discuss plans to update the dominant light-quark connected contribution with increased statistics and additional scale-setting schemes. A companion talk will present the status of the isospin-breaking calculation. All calculations are performed on 2+1+1 flavor HISQ ensembles with a physical pion mass.

Speaker: Shaun Lahert

10:20 Towards hadronic light-by-light contribution to the muon g-2 with C* boundary conditions

The hadronic light-by-light (HLbL) contribution is the second-largest source of theoretical uncertainty in the Standard Model prediction of the muon g-2. Within the RC programme, we are developing an independent HLbL calculation with C boundary conditions using openQxD, based on the two-current subtraction method proposed by Hayakawa, Blum, Izubuchi and Yamada in 2005. As a controlled proof of concept, we compute the analogous leptonic LbL contribution in quenched QED, benchmarked against the perturbative Laporta–Remiddi result, and present a preliminary analysis on the coarsest of several ensembles. We discuss the signal-to-noise problem in this approach and its implications for the planned computation in full QCD+QED.

Speaker: Khai Phan (ETH Zurich)

09:00 → 10:40 Structure of hadrons and nuclei

Convener: Michael Engelhardt

09:00 Inferring Parton Distributions with Gaussian Processes

Extracting parton distribution functions (PDFs) from Lattice QCD is crucial for understanding nucleon structure, but it fundamentally relies on solving a challenging ill-posed inverse problem. In this talk, I will present an overview of my work on addressing this problem within the pseudo-PDF framework. First, I will outline how Gaussian processes (GPs) provide flexible Bayesian priors that encode correlations and physical constraints without fixing a functional shape. Then, I will explain the different levels of inference from which one can obtain different types of reconstruction. Finally, I will show how to integrate all the models explored into a model selection/averaging procedure to obtain a more robust reconstruction of PDFs using different information criteria.

Speaker: Yamil Cahuana Medrano (William and Mary)

09:20 Nucleon Unpolarized PDFs from Lattice QCD at Physical Point with High Boost

We present a lattice QCD calculation of the nucleon unpolarized parton distribution functions (PDFs) at the physical point, with the nucleon boosted to $P_z = 1.78$ and $2.29$ GeV. At a lattice spacing $a = 0.076$ fm, these momenta correspond to $a P_z \lesssim 0.9$, so that lattice-discretization artifacts remain under control, in contrast to earlier physical-mass studies that reached larger nominal momenta at coarser spacings. The calculation is carried out on an $N_{\rm f} = 2+1$ ensemble and covers both the isovector and the connected isoscalar channels within the large-momentum effective theory (LaMET) framework. To reach these momenta with sufficient precision, we combine kinematically enhanced nucleon interpolating operators with Coulomb-gauge-fixed quark bilinears, which together suppress the excited-state contamination (ESC) at large $P_z$ and the signal-to-noise degradation at large quark separation. The light-cone PDFs are obtained through next-to-leading-order (NLO) perturbative matching supplemented by next-to-leading-logarithmic (NLL) renormalization-group resummation (RGR), and the matched distributions show good convergence between the two boosts. Combining the valence ($q-\bar{q}$) and full ($q+\bar{q}$) distributions, we reconstruct the quark and antiquark distributions over $x \in [-1, 1]$. The results are in good agreement with the CT18, MSHT20, and NNPDF4.0 global analyses in the moderate-$|x|$ window $0.25 \lesssim |x| \lesssim 0.75$. For the connected isoscalar channel, the antiquark (sea) distribution is substantially underestimated, an expected consequence of omitting the disconnected contributions, which are required for the physical flavor-singlet combination.

Speaker: Qi Shi (Kent State University)

09:40 Direct calculation of parton distributions in momentum space from lattice QCD

Coulomb-gauge quasi-parton distributions can be computed directly in momentum space on a finite lattice, enabled by the commutativity of their renormalization and Fourier transform. This approach removes the formal inverse problem in coordinate-space methods. Our momentum-space pion quasi-distributions agree with coordinate-space results Fourier transformed with asymptotic extrapolation, indicating that the formal inverse problem in the latter is not a concern at this volume. We further extend the framework to higher dimensions and obtain the first 3D image of the pion directly from lattice QCD.

Speaker: Dr Rui Zhang (MIT)

10:00 Bridging Euclidean Methods for Parton Distributions with Machine Learning

I​​n this work, we develop a unified machine learning strategy based on a variational autoencoder inverse mapper (VAIM) to explore the complementarity of the quasi-PDF and pseudo-PDF methodologies. VAIM is a conditional variational autoencoder–based framework that learns a low-dimensional latent representation of nonperturbative QCD information and constructs an inverse map from lattice-measured observables to the underlying partonic structure, enabling a flexible, data-driven reconstruction of PDFs while retaining correlations across different operator insertions and kinematic regimes. Despite a well-grounded theoretical understanding of the interplay between these two approaches, there are currently no established conventions for simultaneously extracting light-cone information from both frameworks in a unified manner. By combining information from the two methods across multiple values of small $z^2$ for the pseudo-PDF method and large $P_z$ for the quasi-PDF method, we aim to investigate how a flexible unified treatment can improve our understanding of higher-twist effects, increase the robustness of lattice determinations of PDFs, and clarify how the quasi-PDF methodology can be more naturally integrated into phenomenological analyses.

Speaker: Alex NieMiera (Michigan State University)

10:20 Imaging protons and partons with lattice QCD

Femtography is the study of 3D femtometer scale images of the proton. Impact Parameter Distributions describe parton structure in terms of the parton's fraction of the total momenta and the location in the transverse plane. These images can be taken by Deeply Virtual Compton Scattering and other inclusive processes and give light on how mass, angular momentum, and mechanical properties are distributed within the proton. Their phenomenological extraction is hindered by an intractable modeling problem known as shadow-GPDs. Lattice QCD calculable matrix elements allow for the extraction of Generalized Parton Distributions whose Fourier transform gives the impact parameter distribution with such a modeling problem. By calculating over a hundred kinematical configurations, we provide the first 3D model of the GPD's x, xi, and t dependence determined from lattice QCD. The Gaussian Process Regression used in the inverse problem will be highlighted as a highly flexible approach consistent with the features of the system such as polynomiality.

Speaker: Joseph Karpie

09:00 → 10:40 Vacuum structure and confinement

Convener: Dr Claudio Bonanno (ITP, University of Bern)

09:00 Setting the physical scale for lattice simulations using the gluon propagator and the understanding of finite size effects

A crucial step in extracting physical predictions from lattice QCD simulations is the scale setting, i.e. the determination of the lattice spacing (a) in physical units. Herein, the relative scale setting for different β’s is discussed, using the Landau gauge gluon propagator computed with large statistical ensembles. After setting the relative scales, finite size effects are observed in the ultraviolet regime and handled in an effective description, inspired in perturbation theory. The new devised procedure is efficient in handling the finite size effects, linking the lattice simulations with continuum perturbation theory for the high momenta regime. Furthermore, the procedure can be extended to handle other Green functions computed within lattice QCD simulations.

Speaker: Orlando Oliveira

OrlandoOliveira_Latt26.pdf

09:20 Step-scaling determination of the SU($N$) $\Lambda$-parameter in the twisted gradient flow scheme

We compute the $\Lambda$-parameter of SU($N$) Yang--Mills theories for $N=3,5,8$ using the step-scaling method. We use the gradient flow scale $t_0$ for scale setting, and we implement the step-scaling method in the twisted gradient flow scheme, a finite-volume renormalization scheme that combines twisted boundary conditions with a coupling defined via the gradient flow. By extrapolating our results for $N=3,5,8$, we also obtain the first determination of the large-$N$ $\Lambda$-parameter that does not rely on asymptotic scaling.

Speaker: Andrea Giorgieri (University of Pisa, INFN)

09:40 Gradient-Flow Actions, Integerness, and Gluonic--Fermionic Topology Matching in SU(3) Yang--Mills Theory

We study topology readout in $SU(3)$ Yang--Mills theory using several gradient-flow actions. We monitor the integerness of the gluonic topological charge $Q(t)$, admissibility-related diagnostics, and the matching between $\mathrm{round} Q(t)$ and the overlap Dirac index as probes of topological sector identification. We compare Wilson, tree-level Symanzik, Iwasaki, and DBW2 flows on Wilson plaquette ensembles at several lattice spacings. Wilson and Symanzik flows are standard choices, but their gluonic topological charge becomes less integer-like and less well matched to the fermionic index at large flow time. In contrast, Iwasaki and DBW2 flows give more stable sector readout. We also find no special feature when the smearing radius $r_{\rm sm}=\sqrt{8t},a$ reaches or exceeds $L/2$, suggesting that the large-flow-time behavior is not a simple finite-volume touching effect but a flow-action dependence of the gluonic topology operator. We further examine how these diagnostics change toward the continuum limit. This study is an $SU(3)$ extension of the flow-action dependence of topology observed in $SU(2)$ Yang--Mills theory in arXiv:2411.14812.

Speaker: Akio Tomiya (Tokyo Woman’s Christian University)

tomiya_2026_v3.pdf

10:00 Dyon Condensation at $\theta=2\pi$ from Wilson-'t Hooft Loops in Yang-Mills Theory

We report a lattice study of the confinement vacuum of $SU(2)$ Yang--Mills theory at $\theta=2\pi$ using Wilson--'t~Hooft loop observables. Although Yang--Mills theories at $\theta$ and $\theta+2\pi$ are unitarily equivalent, recent developments in generalized global symmetries predict that the confining vacua at $\theta=0$ and $\theta=2\pi$ are distinguished as symmetry-protected topological states associated with the $Z_2$ one-form center symmetry. This distinction can be probed through the Wilson--'t~Hooft classification of gapped phases, where monopole and dyon condensation are characterized by different area/perimeter laws of line operators. We formulate the measurement at $\theta=2\pi$ by inserting an 't Hooft defect and evaluating the corresponding topological phase factor. To define the topological charge in the presence of the defect, we employ a one-form covariant DBW2 gradient flow, which stabilizes topological sectors and makes the reweighting factor numerically tractable. Our simulations with the Wilson plaquette action show a clear perimeter-law behavior for the dyonic loop, while the direct signal for the area law of the 't Hooft loop is statistically challenging. These results provide numerical hints for dyon condensation at $\theta=2\pi$, rather than monopole condensation, in agreement with the expected SPT structure of the confinement vacua.

Speaker: Dr Okuto Morikawa (RIKEN iTHEMS)

10:20 Emergence of magnetic monopoles due to violation of the non-Abelian Bianchi identity

The dual superconductor picture is a promising mechanism for quark confinement, and magnetic monopoles play a dominant role in quark confinement. To understand the mechanism of quark confinement, we investigate the relation between the violation of the non-Abelian Bianchi identity (VNABI), the emergence of magnetic monopoles, and confinement by using the gauge-covariant decomposition and the non-Abelian Stokes theorem for the Wilson loop.

We find that the VNABI is reduced to the magnetic monopoles associated with the color-direction fields. Therefore, the emergence of magnetic monopoles causes the VNABI, which contributes to quark confinement. We further conduct numerical simulations and provide numerical evidence.

Speaker: Akihiro Shibata (KEK)

10:40 → 11:10 Coffee break

11:10 → 12:30 Algorithms and artificial intelligence

Convener: Dr Thomas Spriggs (Delft University of Technology)

11:10 Spectral Properties of the non-Hermitian Dirac Operators from the Krylov-Schur Algorithm

The Dirac operator is a fundamental object in lattice gauge theory. Its spectral properties carry direct physical significance: its low modes limit convergence in Krylov-based linear solvers, and real (zero) eigenvalues of the Wilson (overlap) Dirac operator correspond to topologically non-trivial field configurations. While the spectrum of Hermitian Dirac operators is real and easy to compute via the Lanczos algorithm, the complex spectrum of non-Hermitian Dirac operators is more difficult to understand. A particular challenge is computing the interior eigenmodes of non-Hermitian Dirac operators, which are naturally suppressed in Krylov-based methods. In this talk, I will present the first application of the Krylov-Schur eigenvalue algorithm to lattice gauge theory. Its harmonic extension can be used to access interior eigenmodes of non-Hermitian Dirac operators. I will contrast the Krylov-Schur algorithm with the standard Arnoldi iteration, and discuss an application of how the Krylov-Schur algorithm may be used better understand the convergence of multigrid solvers.

Speaker: Patrick Oare (Brookhaven National Laboratory)

11:30 Topological modes in Lattice QCD evolution

Despite the intrinsic ambiguity in defining the topological index $Q$ on a discrete lattice, fermionic definitions based on either the Hermitian or non-Hermitian Wilson–Dirac operator yield an integer-valued topological index for any lattice QCD configuration. Here, we focus on configurations in which the topological index changes during the Hybrid Monte Carlo evolution, and investigate the properties of the Dirac eigenmodes that are directly responsible for these changes in $Q$.

Speaker: Chulwoo Jung

11:50 Learning Low Modes of the Wilson Dirac Operator with Gauge-Equivariant Networks

The low-lying modes of the Wilson Dirac operator are key ingredients in deflation and multigrid algorithms for lattice QCD, where they define the near-null spaces responsible for critical slowing down. In this talk, we present a method for learning such low modes with a gauge-equivariant neural network trained on an ensemble of gauge configurations, using a Rayleigh–Ritz loss that minimizes the sum of the lowest Rayleigh quotients of $D^\dagger D$. Because the network is trained across the ensemble rather than per configuration, its setup cost can be amortized over many solves. We report the generalization of the learned modes to held-out configurations on small lattices, and demonstrate their effectiveness as test vectors in the DD-$\alpha$AMG multigrid solver.

Speaker: choi minjae

12:10 Updates on the Machine Learning Approach for Lattice Gauge Fixing

Machine learning offers an alternative to conventional iterative algorithms for lattice gauge fixing, with the potential to reduce computational cost for large lattice volumes. Building upon our previous work, we perform a systematic scan of convolutional neural network architectures for lattice gauge fixing, in which the gauge transformation matrices are constructed from Wilson lines with multiple lengths. We explore the trade-off between gauge-fixing performance and computational efficiency, identifying compact models that maintain competitive performance while reducing computational cost, particularly on large lattices. We present preliminary results on SU(3) gauge ensembles, demonstrating that an appropriate model design can provide an efficient and scalable approach to lattice gauge fixing.

Speaker: Ho Hsiao (Center for Computational Sciences, University of Tsukuba)

11:10 → 12:30 Hadronic and nuclear spectrum and interactions: I

Convener: Sebastian Dawid (Indiana University Bloomington)

11:10 Scattering length in the $O(4)$ non-linear sigma model

We investigate the determination of the $s$-wave scattering length in the $O(4)$ $\phi^4$ theory in the symmetry-broken phase. The theory is simulated on a four-dimensional lattice in the strong-coupling limit with a small external symmetry-breaking term. This model provides a controlled setting for testing methods used to extract low-energy scattering observables from lattice simulations.
We focus on the isospin-$0$ and isospin-$2$ two-pion channels and compare perturbation theory, the finite-volume formalism of Lüscher, and the Euclidean correlator approach of Maiani and Testa for the extraction of the scattering length. Particular attention is paid to the the signal-to-nosie problem of the Maiani-Testa approach and its impact on the practical determination of scattering observables.

Speaker: Raphael Lehner

11:30 A perturbative $N$-particle finite-volume formalism

Understanding coupled-channel dynamics involving three or more particles remains a major challenge for computing hadronic scattering and decay processes on the lattice. We present a perturbative framework for describing such systems involving an arbitrary number of particles in a finite volume. Our method is valid at leading order in all $n\to m$ couplings of the theory, and incorporates the finite-volume effects associated with leading-order subprocesses in every sector with three or more particles. We present the resulting quantisation condition and discuss its domain of validity. We also discuss an extension to a hybrid formalism that combines a non-perturbative treatment of two-particle dynamics with a perturbative treatment of sectors containing three or more particles. Finally, we outline potential applications to multi-hadron processes relevant to lattice QCD.

Speaker: Rajnandini Mukherjee (University of Edinburgh)

11:50 FVU 3-body quantization condition: developments and applications

Since its derivation, the Finite-Volume Unitarity (FVU) 3-body quantization condition became a working horse studying various phenomenologically interesting systems from lattice. This includes pi(1300), omega(782) or a1(1260).

In my talk I will review new theoretical developments and updates in view of recent and anticipation of upcoming applications from lattice QCD.

Speaker: Maxim Mai (University of Bern)

12:10 Energy dependence of two-pion transitions

We extract the elastic electromagnetic transition of a two-pion $I=2$ state across the two-pion elastic energy region using lattice QCD. In particular, we determine the energy dependence of a two-particle transition from lattice QCD for the first time. The finite-volume spectrum and elastic matrix elements were calculated on a lattice with $m_\pi\approx 400$ MeV. Infinite-volume amplitudes were then extracted by removing leading power-law finite-volume effects according to the Lüscher formalism and its extensions. This work provides a proof of principle, as the same finite-volume techniques can be applied to systems featuring shallow bound states or resonances, allowing for the removal of finite-volume effects in their form factor extractions. Access to the form factors of these states is an important step toward understanding of QCD and its confining mechanism, while also providing valuable constraints for electroweak interactions with multi-nucleon systems.

Speaker: Felipe Ortega Gama (UC Berkeley)

11:10 → 12:30 Hadronic and nuclear spectrum and interactions: II

Convener: John Bulava

11:10 Inclusive P-wave quarkonium decay widths in pNRQCD

In pNRQCD, the inclusive P-wave heavy quarkonium decay width into light hadrons factorizes at a scale $\Lambda$, and the non-perturbative contribution reduces to $\mathcal{E}_3$, an integral over the correlator of two electric fields connected by an adjoint Wilson line. This correlator is universal, independent of the specific initial state. In this work, we developed a new method that employs gradient flow to subtract the power divergence of the Wilson line and to match the chromoelectric correlator to the $\overline{\mathrm{MS}}$ scheme. These are the first non-perturbative results for the chromoelectric correlator at zero temperature, and we present with them first-principles results for P-wave decay widths of charmonium and bottomonium.

Speaker: Julian Mayer-Steudte

11:30 $\eta$ and $\eta'$ production in radiative decays of charmonium

We present a first-principles lattice QCD calculation of the radiative transitions of charmonium states to the light pseudoscalar mesons $\eta$ and $\eta'$. We extract the relevant transition form factors as a function of photon virtuality and connect the timelike region accessible through Dalitz decays to the real-photon point. A recurring challenge in these calculations is the appearance of the $\eta'$ as an excited state of the pseudoscalar isoscalar tower. We address this through variationally optimised operators for both the charmonium and light-quark mesons. To manage the noisy disconected process we use a dedicated correlator-averaging strategy that yields clean signals at a dense set of kinematic points. We illustrate the methodology and discuss results across several channels, highlighting the expected difference in $\eta'$ and $\eta$ production and the prospects for extending these techniques to further charmonium transitions and to processes involving genuine light-meson resonances.

Speaker: Mischa Batelaan (Adelaide University)

11:50 Hybrid spin-dependent and hybrid–quarkonium mixing potentials at large quark–antiquark separations from lattice gauge theory

We present $\text{SU}(3)$ lattice gauge theory results for the $\mathcal{O}(1/m_Q)$ hybrid spin-dependent and hybrid–quarkonium mixing potentials. The only existing lattice computation of these potentials was exploratory and limited to quark–antiquark separations below approximately $0.5\,\mathrm{fm}$. We extend the lattice determination beyond $1\,\mathrm{fm}$ using large-volume, high-statistics simulations at several lattice spacings and gradient-flow times, providing the first nonperturbative data in this previously inaccessible regime. We discuss the impact of these results on Born–Oppenheimer effective field theory predictions of conventional and hybrid quarkonium.

Speaker: Vilija de Jonge (Institut für theoretische Physik an der Goethe Universität Frankfurt am Main)

12:10 $\omega(782)$ and $\phi(1020)$ from lattice QCD

Understanding hadron interactions from QCD is key to mapping out the resonance spectrum of the strong interaction. In recent years, lattice QCD has made significant progress in treating both two- and three-body scattering, but a description of coupled systems involving both remains lacking.

In this talk, we present a study of the isoscalar vector sector in a coupled two- and three-body framework. Building on our previous investigation of the $\pi\pi\pi$ channel, we extend the analysis to include $K\bar{K}$ states and study $\omega$-$\phi$ mixing within the finite-volume unitarity (FVU) formalism. We extract finite-volume spectra and scattering amplitudes, and discuss the resulting pole structure and mixing parameters.

Speaker: Haobo Yan (Peking University)

11:10 → 12:30 Quantum computing and quantum information

Convener: Tanmoy Bhattacharya (Los Alamos National Laboratory)

11:10 Preparation and detection of quasiparticles for quantum simulations of scattering

We introduce a method for the selective preparation and detection of quasiparticle wave packets, based on creation operators that generate dressed, localized excitations on top of interacting vacua of (quasi-)one-dimensional quantum lattice theories. This method exploits maximally localized Wannier functions (MLWFs) constructed from quasiparticle bands at intermediate system sizes, enabling the construction of unitary local dressed creation operators. The algorithm allows for species-resolved wave-packet preparation and detection, enabling the separation of known quasiparticle contributions from unknown resonances. We test this approach with matrix product states (MPS) on pure hardcore Hamiltonian QCD on a ladder lattice, detecting scattering outputs and mass resonances.

Speaker: Mattia Morgavi (Università degli Studi di Padova)

11:30 Quantum Complexity in Simulations of Scattering in the XZ Heisenberg Model

In classical simulations of quantum many body systems, entanglement has served as the traditional measure of "quantumness" or computational complexity. This was until the Gottesman-Knill theorem showed that a certain class of quantum states known as stabilizer states, which include some maximally entangled states, can be simulated classically with complexity linear in the number of qubits via the stabilizer tableau formalism. Thus, a true measure of complexity will involve both entanglement and nonstabilizerness (magic) of the states in a simulation. Using the complexity measures (1) bipartite entanglement entropy and (2) antiflatness, a lower bound for linear bipartite non local magic, we investigate quantum resource distribution in position space scattering simulations of an XZ Heisenberg model. We begin in the limit of a disordered Ising model ($h>J_x>>J_z$) and gradually ramp up $J_x$ and $J_z$ maintaining $J_x>J_z$, and also explore volume effects. We report on recent progress regarding the implications of this analysis for tensor network design and quantum simulations for both 1+1D and 2+1D models.

Speaker: Michael Hite (University of Arizona)

11:50 Finite-Volume Errors on Real-Time Estimators for Scattering Observables

Real-Time Estimators for Scattering Observables (RESOs) is a proposal for the extraction of scattering amplitudes from simulations on quantum computers. Unlike the Lüscher family of methods on traditional Lattice QCD, RESOs shows that access to real-time correlators, increasingly achievable through quantum hardware, permits the study of general reactions without formal roadblocks associated to the energies involved. In order to show this, in 2506.06511 we explored the finite-volume effects of generic scattering processes in perturbation theory. In this talk we will show how the Feynman epsilon prescription suppresses finite-volume effects, and we will further show how we can enhance this suppression through a restoration of Lorentz invariance by averaging results in multiple frames.

Speaker: Ivan Mauricio Burbano Aldana (University of California, Berkeley and Lawrence Berkeley National Laboratory)

12:10 Toward quantum computation of hadronic tensors

Hadronic tensors encode non-perturbative information about hadron structure and scattering dynamics. Quantum computing offers a complementary first-principles approach to kinematic regimes challenging for classical algorithms. As a proof-of-concept study, we investigate the scalar-current hadronic tensor in a deep-inelastic scattering in the Schwinger model. We evaluate the corresponding real-time current-current correlator using quantum-circuit methods and obtain the hadronic tensor through Fourier transformation. We present the results for circuit executions in a 10-site theory. This work benchmarks quantum-simulation approaches to hadronic tensors and lays the groundwork for future applications in hadronic physics.

Speaker: Chung-Chun Hsieh (University of Maryland, College Park)

11:10 → 12:30 Quark and lepton flavor physics

Convener: Ethan Neil

11:10 The isospin violating part of the HVP

We present our latest results on the isospin violating part of the HVP in the muon (g-2), including a chiral continuum extrapolation, where all relevant diagrams and the necessary counterterm enter. We use the covariant coordinate-space representation (CCS), and, following our recent work [2603.13086], we employ a factorization of the position space photon propagator for a suitable subset of the quark-level diagrams.

Speaker: Dominik Erb

Dominik_Erb_Lat2026.pdf

11:30 Improved calculational setup for isospin-breaking corrections to the HVP contribution to g-2

Isospin-breaking corrections to the hadronic vacuum polarization contribution to the muon g-2 are one of the largest contribution to the error in the latest lattice calculations. To reach the precision of the direct measurement of the muon anomalous magnetic moment, it is therefore crucial to reduce the uncertainties contributing to the total error of hadronic vacuum polarization. I will present preliminary results from a new calculational setup that improves the statistical precision for constant numerical cost. Additionally, contributions coming from disconnected diagrams which are traditionally difficult to obtain from the lattice, can now be measured with reasonable numerical effort.

Speaker: Sebastian Lahrtz (Johannes Gutenberg-University Mainz)

11:50 Strong isospin breaking: comparing $N_{f}=1+1+1$ simulations and the RM123 method

The inclusion of isospin-breaking contributions is mandatory for achieving sub-percent precision in determinations of the hadronic vacuum polarization (HVP) and demands efficient computational strategies. In this talk, I compare two approaches: explicit $N_f = 1+1+1$ simulations with non-degenerate up and down quark masses, and the RM123 perturbative expansion in the quark mass splitting $\Delta m$ applied to a $N_f = 2+1$ ensemble. Using two CLS ensembles at the same lattice spacing, I compute several observables sensitive to strong isospin breaking, including the isovector-isoscalar HVP contribution $a_\mu^{\mathrm{HVP},38}$, and compare the statistical efficiency of both approaches.

Speaker: David Albandea (Helmholtz-Institut Mainz, GSI)

12:10 ETMC calculation of $a_\mu^{\rm HVP}$ in isospin-symmetric QCD

We calculate the hadronic vacuum polarization (HVP) contribution to the muon's anomalous magnetic moment using isospin-symmetric lattice QCD. The calculation is based on gauge configurations generated by the Extended Twisted Mass Collaboration (ETMC) with $N_f = 2 + 1 + 1$ flavors of Wilson-clover twisted-mass quarks, employing four lattice spacings between $0.045$ and $0.08\text{ fm}$ and spatial volumes up to $L$ up to $7.7\text{ fm}$.

Speaker: marco garofalo (University of Bonn, HISKP)

11:10 → 12:30 Structure of hadrons and nuclei

Convener: Jonna Marjaana Koponen (Bergische Universität Wuppertal)

11:10 Structure functions for lepton-nucleon scattering from four-point functions on the lattice

The hadronic tensor is the central non-perturbative object in the calculation of the cross section of lepton-hadron interactions like neutrino-nucleon scattering. It is parameterized in terms of structure functions, which encode all necessary information independently of the kinematic region. We calculate correlation functions of two currents with Euclidean time separation using a clover fermion ensemble at pion mass $m_\pi = 223~\mathrm{MeV}$ and lattice spacing $a=0.085~\mathrm{fm}$. The resulting Euclidean matrix elements are linked to the hadronic tensor via a Laplace transform. We show some results for vector and axial vector currents and compare with experimental data.

Speaker: Christian Zimmermann (University of Kentucky)

11:30 Nachtmann moment of the parity-violating structure function from Feynman-Hellmann

Precision determinations of $V_{ud}$ from superallowed nuclear β decays provide an important test of the Standard Model. A leading theoretical uncertainty arises from electroweak radiative corrections, in particular the contribution from the $\gamma W$ box diagram involving the interference between the electromagnetic and axial currents. The closely related $\gamma Z$ box contribution may be written as a dispersion integral over the parity-violating structure function $F_3^{γZ}$, which motivates a determination of its first Nachtmann moment at low $Q^2$.
On behalf of the QCDSF collaboration, we present a lattice QCD calculation of the first Nachtmann moment of $F_3^{γZ}$ using the Feynman-Hellmann method. Our calculations employ $N_f=2+1$ flavours of dynamical fermions at the SU(3)-symmetric point, using three lattice spacings with pion masses $m_\pi≈415$ MeV and $220$ MeV, for various momentum transfers in the range $0.1\lesssim Q^2\lesssim 10$ $\text{GeV}^2$.

Speaker: Jordan Mckee

11:50 Proton isovector helicity PDF and the twist-3 moment $\tilde{d}_2$ from lattice QCD at physical quark masses

We present lattice QCD calculations of the proton isovector quark helicity parton distribution function (PDF) within the Large Momentum Effective Theory (LaMET) framework, together with the first determination of the twist-3 moment $\tilde{d}_2$ from the operator product expansion of nonlocal matrix elements. The helicity PDF is calculated using both gauge-invariant (GI) and Coulomb-gauge (CG) quasi-PDF constructions. The GI quasi-PDF is computed on a HotQCD ensemble with lattice spacing $a=0.076$ fm, pion mass $m_\pi=140$ MeV, and proton momentum $P_z=1.53$ GeV, while the CG quasi-PDF is simulated on a second ensemble with $a=0.06$ fm, $m_\pi=300$ MeV, and $P_z=2.43, 3.04$ GeV. The resulting helicity PDFs agree within uncertainties for $0.25\lesssim x\lesssim0.5$. At larger $x$, the CG results fall more rapidly and are in better agreement with recent global analyses, likely because the larger $P_z$ suppresses LaMET power corrections. We also obtain $\tilde{d}_2^{u-d}(2,\mathrm{GeV})=0.0024(46)$ in the $\overline{\mathrm{MS}}$ scheme at next-to-leading order, indicating a small genuine twist-three contribution.

Speaker: Yong Zhao

12:10 Spatial Densities without Form Factors

It has been taken for granted in lattice formulation that, due to translational invariance, it is not feasible to have a reference point to define the spatial densities of local operators in a hadron. We shall show that, using Ward identity, one can find the positions of valence quarks so that the spatial densities can be defined and calculated. This bypasses the usual practice of obtaining spatial densities from the Fourier transforms of form factors, which have been shown not to be valid due to uncontrolled relativistic effects. We will present lattice results of the pion charge density from both approaches to illustrate the difference.

Speaker: Prof. Kehfei Liu (Lawrence Berkeley National Lab)

11:10 → 12:30 Vacuum structure and confinement

Convener: Akihiro Shibata

11:10 Ground States of adjoint SU(2) from Neural Newtork assisted Variational Montecarlo

Gauge theories with matter fields in the adjoint representation play an important role in the mechanisms of confinement due to an additional unbroken center symmetry. Assessment of the vacuum groundstate are, therefore, of primary interest in calculation of order parameters, monopole mass and center vortices. To this end, we present some results from an ongoing study of the adjoint SU(2) gauge-Higgs theory in $2+1$ and $3+1$ dimensions using a recently developed neural network wavefunction approach to the Variational Montecarlo technique.

Speaker: David Ward (National Taiwan University)

11:30 Confining flux tube in the trace deformed (2+1) dimensional $\mathrm{SU}(2)$ gauge theory

We investigate the properties of the confining flux tube within the reconfined phase of trace-deformed $\mathrm{SU}(2)$ Yang-Mills theory in $(2+1)$ dimensions. Using lattice simulations performed above the standard deconfinement temperature, we analyze Polyakov-loop correlators to determine the ground-state energy of the effective string. Our numerical results indicate that the conventional Nambu-Goto effective string description, even when accounting for standard higher-order corrections, fails to model the data as the trace-deformation parameter is increased. Conversely, deep within the reconfined regime, the effective string behavior is accurately captured by the Polchinski-Yang rigid-string solution, which features an effective string dominated by an extrinsic-curvature term. Additionally, we investigate the phase diagram and find evidence that the reconfinement line transitions from continuous to first-order with increasing deformation. Our results suggest that confinement in the reconfined phase is governed by a qualitatively different effective-string regime than standard confinement.

Speaker: Dario Panfalone

11:50 Flux Tube Entanglement Entropy across Temperature, Geometry, and Gauge Group

We study the vacuum-subtracted entanglement entropy of the color flux tube between a static quark-antiquark pair in SU(2) through SU(5) (2+1)-D pure gauge theory. Using the replica trick, we examine the dependence of entanglement on temperature as well as the size and topology of the entangling region. Through analyzing these factors, we present quantitative conclusions about the nature of non-abelian flux in both confining and deconfining regimes, finding signatures of the intrinsic width as well as a new scale, the entanglement radius, that characterizes a "thickness" of the flux tube distinct from the intrinsic width.

Speaker: Rocco Amorosso

12:10 I = 2 pion scattering length in the large-$N$ limit

We present a lattice determination of the I = 2 pion scattering length in the large-$N$ limit. This calculation is based on the twisted Eguchi-Kawai formulation of large-$N$ QCD, and employs values of $N$ ranging from 289 up to 1156. Our findings will be compared with Chiral Perturbation Theory predictions and with previous large-$N$ lattice results obtained with standard methods and extrapolating from $N \le 6$.

Speaker: Dr Claudio Bonanno (ITP, University of Bern)

12:30 → 13:00 Lunch break (boxed lunch)

13:00 → 18:00 Excursion to Washington DC

If you have an excursion transportation ticket, please follow organizers' instructions to proceed to buses.

Thursday 30 July

09:00 → 10:30 Plenary session

Convener: Max Hansen

09:00 (Heavy) hadron exotics from lattice QCD

I shall present a review of recent developments in meson-meson and meson-baryon spectroscopy from lattice QCD, with particular attention to studies of exotic hadron candidates involving heavy quarks. Due emphasis shall be laid on the experimental and phenomenological significance of these investigations, with a view to bringing out the emerging consensus, the outstanding open questions, and the future directions that lattice QCD studies are likely to take in elucidating the nature and internal dynamics of these exotic states.

Speaker: Dr M. Padmanath (The Institute of Mathematical Sciences Chennai)

Padmanath_lattice2026_HadronExotics

09:30 Nuclear and hypernuclear physics from lattice QCD

Lattice quantum chromodynamics (LQCD) offers the tantalizing prospect of grounding nuclear physics in the fundamental theory of the strong force. Besides the importance of these calculations to reveal the emergence of nuclear complexity from the Standard Model, current theoretical modelling of nuclear targets used in experimental searches for physics beyond the Standard Model often lead to relatively large systematic uncertainties, limiting the "discovery potential" of these experiments. Thus, LQCD can contribute to these experimental programs, if we can demonstrate systematically controlled nuclear and hypernuclear calculations. While conceptually straightforward, nuclear-scale energy gaps and an exponentially hard signal-to-noise problem make these systems challenging to study. In this talk, I will discuss the recent progress towards systematically controlled nuclear and hypernuclear calculations.

Speaker: Robert Perry (Massachusetts Institute of Technology)

10:00 Lattice Field Theory Meets Quantum Computers

Quantum simulation is widely considered to be the most promising application of quantum computers. Already, robust experiment-theory collaborations targeting lattice field theory simulations have pushed the limitations of ever-improving quantum hardware, establishing performance benchmarks [1], providing an arena for quantum co-design [2], and motivating hardware innovation [3,4]. This talk will touch on three leading hardware platforms for quantum computation and simulation: trapped ions, neutral atoms and superconducting qubits. I will summarize the capabilities of state-of-the-art devices commercially available, compare pros and cons between platforms, and highlight recent advances outside of industry which may provide alternative routes to utility-scale computation. Finally, I will challenge the audience to work on problems currently plaguing the intersection between experiment and theory.

[1] Muschik et al. NJP (2017)
[2] Davoudi. arXiv:2605.20417 (2026).
[3] Than et al. Nat. Comms. (2025)
[4] Than et al. arXiv:2509.11477 (2025).

Speaker: Alaina Green (Joint Quantum Institute / U. Maryland)

10:30 → 11:00 Coffee break

11:00 → 12:30 Plenary session

Convener: Nilmani Mathur

11:00 Theoretical and algorithmic foundations of quantum simulation of gauge theories

Speaker: Christian Walter Bauer (Lawrence Berkeley National Lab. (US))

11:45 Wilson Award Session

Speaker: Prof. Zohreh Davoudi (University of Maryland)

12:30 → 14:00 Lunch break

14:00 → 15:40 Algorithms and artificial intelligence

Convener: Daniel Hackett

14:00 Solving sign problems with physics-informed kernels

In this talk we present a novel generative architecture for systems with complex probability distributions. In general, these sampling tasks come with two challenges: resolving sign problems and efficient sampling. The architecture is based on physics-informed kernels (PIKs) introduced in arXiv:2510.26678, and aims at resolving both challenges. Key to the complex PIK-architecture is its probability-weight preserving property, which allows us to map the sampling task to one on a sign-problem free manifold with a simple distribution and efficient sampling. The potential of this novel architecture is demonstrated within applications to zero-dimensional field theories with complex couplings, as well as the real-time evolution of the quantum-mechanical harmonic oscillator.

Speaker: Renzo Kapust (Universität Heidelberg)

14:20 Learning the generating functional for variance reduction in lattice QCD

The generating functional in quantum field theory provides the natural framework for constructing correlation functions as derivatives with respect to source operators. In this talk, I will present a methodology that leverages machine-learned normalizing flows to reduce the variance of arbitrary N-point correlation functions of bosonic operators in lattice gauge theory calculations by encoding a representation of the generating functional. I will show that this framework makes it possible to systematically approach noiseless estimators of correlation functions. I will demonstrate the methodology with applications to glueball correlation functions and Wilson loops in Quantum Chromodynamics and Yang-Mills theory, where we observe up to three orders of magnitude variance reduction.

Speaker: Fernando Romero López (Uni Bern)

14:40 Neural-Enhanced Out-of-equilibrium sampling for Lattice Field Theory

In recent years, the combination of neural network architectures and out-of-equilibrium methods has emerged as a powerful framework to build a new generation of numerical algorithms in various scientific fields. In lattice field theory, a prominent example is Stochastic Normalizing Flows, which have been used to tackle topological freezing in $\textrm{SU}(3) $ gauge theory. In this talk, we briefly introduce out-of-equilibrium sampling methods and how to enhance them with neural networks. We then discuss a general approach for the large-scale training of Neural-Enhanced Out-of-equilibrium (NEO) methods based on Parallel Tempering and well-suited loss functions, showcasing numerical results for the $\textrm{O}(3)$ non-linear sigma model. We conclude by discussing potential future directions for NEO methods, highlighting the search for novel scenarios or algorithmic synergies, such as multiscale approaches, where these algorithms can enable novel simulation strategies.

Speaker: Elia Cellini (University of Edinburgh)

15:00 Unbiased Diffusion-Based Generation via Scalable Non-Equilibrium Transport

Sampling with flows and diffusion models has emerged as a promising alternative to MCMC in lattice field theory. A central obstacle to their practical adoption is the degradation of sample quality as the lattice volume grows, and identifying a scalable prescription for applying deep generative models to the lattice setting is still an open problem. We adapt and extend a framework based on non-equilibrium transport sampling (NETS) as a continuous-time generalization of annealed importance sampling. Our approach enables diffusion-based generation that remains asymptotically unbiased by accumulating dynamical reweighting factors along the interpolating trajectory at inference time, with the effective sample size systematically refinable through tunable post-training parameters and no retraining. We illustrate our method by training energy-based diffusion models in the context of scalar field theory and the ${\rm O}(3)$ sigma model, demonstrating monotonic improvement of the ESS and reduction in the variance of the importance weights with the number of integration steps and strength of the stochastic transport term.

Speaker: Octavio Vega (University of Illinois Urbana-Champaign)

15:20 Renormalization Group inspired inverse blocking with conditional normalizing flows

Critical slowing down remains a major challenge for lattice simulations near continuous phase transitions, where the correlation length diverges. One possible strategy to address this issue is to generate large-volume configurations from smaller lattices, where local update algorithms remain efficient. In this setting, the renormalization group provides a natural framework: the coarse configuration constrains the infrared degrees of freedom, while only the missing ultraviolet modes need to be reconstructed. Rather than constructing a perfect action for a fixed blocking transformation, we investigate the complementary idea of constructing what we term a "perfect blocking" transformation, chosen such that the RG flow approximately preserves the target action. This allows coarse configurations to be generated from a known probability distribution and subsequently upscaled to a larger volume with an exact accept/reject correction. We present the formulation of this framework and its implementation for the two-dimensional $\phi^4$ theory. The conditional normalizing-flow reconstruction of the ultraviolet degrees of freedom is briefly outlined.

Speaker: Letizia Parato (University of Colorado - Boulder)

14:00 → 15:40 Hadronic and nuclear spectrum and interactions

Convener: Rajnandini Mukherjee (University of Edinburgh)

14:00 Analysis of isospin-zero two-pion scattering using rebased GEVP with physical quark masses

We present a systematic study of the finite-volume spectrum of isospin-zero two-pion scattering using lattice QCD with physical quark masses and G-parity boundary conditions. This is a reanalysis of the data used for the 2020 RBC&UKQCD calculation of $\epsilon’$. Our main focus is the extraction of the ground-state energy, which is critical for computing the $I=0$ $K \to \pi \pi$ decay amplitude with physical kinematics, which combined with the $I=2$ amplitude gives $\epsilon’$, a measure of the Standard Model direct CP-violation in the kaon system. Our analysis employs the generalized eigenvalue problem to isolate finite-volume energy levels using 3 and 2 operators. We further compare the standard GEVP approach with a “rebased” GEVP procedure. Obtaining precise and robust results for this system is challenging because of noisy disconnected diagrams, nearby excited-state contamination, the rapid decay of the signal-to-noise ratio and fit choices. Our results provide a systematic assessment of these methodologies and challenges.

Speaker: Clement Charles (University of Maryland)

14:20 Isotensor Three-Pion Scattering from Lattice QCD

I will present a first-principles calculation within Quantum ChromoDynamics (QCD) of strongly coupled isotensor three-pion scattering amplitudes with resonating sub-channel $\rho$ mesons. Computations within lattice QCD allow for a systematic determination of the spectrum of three pions in a finite-volume. Using generalizations of the L\”uscher framework, we map the spectrum to infinite-volume scattering amplitudes. I will present an overview of this program, discuss developments in determining three-hadron scattering processes using lattice QCD, and showcase the new results for isotensor three pions. Prospects for future applications will be discussed.

Speaker: Andrew Jackura (William & Mary)

14:40 Two- and three-pion scattering in multiple three-body isospin channels

In this talk, we present two and three pion scattering using finite volume spectra from lattice QCD. We discuss three-pion scattering in both the maximal isospin and isotensor channels, the latter of which exhibits a $\rho$ resonant subsystem. The different three-pion channels rely on knowledge of the same two-pion subchannels with $I_{2\pi}=2,1$. We explore the importance of simultaneous fits to two- and three-body spectra to properly account for correlations in determining the relevant scattering amplitudes. The lattice spectra used include multiple volumes from ensembles with $M_{\pi}\approx400$ MeV generated by the Hadron Spectrum Collaboration.

Speaker: Jacob Sitison (University of Colorado Boulder)

15:00 Symmetrizing Three-body Partial-Wave Amplitudes

Three-body dynamics play an important role within the hadron spectrum, from familiar resonances like the omega meson to more exotic states such as the recently-discovered T_{cc} tetraquark candidate. The complete Lüscher workflow has been formalized for a growing number of three-hadron systems, and lattice QCD calculations of these systems are underway. Given a set of lattice-determined K-matrices, the infinite-volume partial-wave scattering amplitudes are obtained from integral equations that are asymmetric with respect to the choice of spectator. We present a concluding step in this workflow, in which the asymmetric amplitudes are symmetrized. We apply the symmetrization procedure to a toy-model three-pion amplitude with lattice QCD input and, using Dalitz plots, demonstrate that the resulting symmetrized amplitudes exhibit the expected symmetries of a three-pion interaction.

Speaker: Nicholas Chambers (William & Mary)

15:20 Staggered pions in a finite volume and their scattering amplitudes

Staggered fermions comprise an important theoretical framework in modern lattice QCD calculations due to their low computational cost. However, the theory manifests highly non-trivial lattice artifacts that complicate the extraction of scattering amplitudes from finite-volume energies using the Lüscher formalism. At non-zero lattice spacing, the meson sector of the theory contains multiple non-mass-degenerate pions as a result of taste splitting, thus requiring the fourth rooting procedure to recover the correct number of pions in the continuum limit. This procedure, however, is known to break unitarity of the quantum theory. Although these artifacts vanish in the continuum limit, it remains a challenge to extract scattering amplitudes from staggered lattice data at non-zero lattice spacing. In this talk, we focus on pion-pion scattering amplitudes and present recent developments towards a generalized formalism that accounts for $\mathcal{O}(a^2)$ staggered lattice artifacts in the scattering amplitude. Our central observation is that the multiple pion tastes naturally enter the formalism via coupled-channel scattering that reduces to a single channel in the continuum limit.

Speaker: Dr Adeilton Dean Marques Valois (University of Granada)

14:00 → 15:40 QCD at nonzero temperature and density

Convener: David Clarke

14:00 Finite-density equation of state of hot QCD using the complex Langevin equation

This talk presents the results of lattice simulations of quantum chromodynamics (QCD) above the crossover temperature and at unprecedentedly high baryon densities. Lattice QCD calculations at finite chemical potential suffer from the sign problem, which prevents the use of conventional importance-sampling methods such as the Hybrid Monte Carlo algorithm. In this study, the Complex Langevin equation is employed to circumvent this problem. The simulations are performed at the physical point, and the results are extrapolated to the continuum limit. In particular, we determine the QCD equation of state by computing thermodynamic observables, including the baryon density, pressure, energy density, entropy density, trace anomaly, and speed of sound, as functions of the baryon chemical potential and temperature. Potential issues related to incorrect convergence of the Complex Langevin dynamics are under control, and we find agreement with previous lattice studies at lower chemical potentials, as well as with perturbative hard-thermal-loop calculations at high temperatures.

Speaker: Daniel Unterhuber (University of Graz)

14:20 Canonical partition function and equation of state in the heavy quark region of finite-density lattice gauge theory

We investigate the phase structure and equations of state in lattice gauge theory at finite temperature and finite density, focusing on the canonical partition function obtained by expanding the grand partition function in terms of particle number. We demonstrate that when quark masses are heavy and the hopping parameter expansion of the quark determinant is applicable, the complex phase of the quark determinant, which causes the sign problem, can be controlled by decomposing the grand partition function according to particle number. In this study, we propose an algorithm to calculate the canonical partition function for heavy-quark, high-density effective theory and first tested it using SU(2) gauge theory with one-flavor, a case where the sign problem arises. When the grand partition function of SU(2) is decomposed into canonical partition functions, it can be seen that the sign problem is serious in the part with an odd number of particles, while it is not so serious in the part with an even number of particles. Furthermore, the odd-particle sectors present a fundamental problem. Due to the center symmetry of the theory, the canonical partition function of SU(N) gauge theory vanishes unless the particle number is an integer multiple of N. While this is valid in the confinement phase, it is physically incorrect in the deconfinement phase. We resolve this issue. We perform Monte Carlo simulations, calculate the canonical partition function without the sign problem, and reconstruct the grand partition function. Then, we compute the equation of state for thermodynamic quantities and the behavior of order parameters across the entire range of temperature and density.

Speaker: Shinji Ejiri (Niigata University)

14:40 Analytic continuation from imaginary chemical potential, via a Cauchy formula inverse problem: state of the art

The sign problem interdicts lattice simulations at real non-zero values of the chemical potential: the computation of observables at imaginary values is a popular way out, but to make predictions for QCD at finite density one is left with the problem of the analytic continuation to the real axis, given a discrete set of measurements on the imaginary one. The Parma group has developed a method based on the Cauchy integral formula, which is first discretised à la Gauss Legendre and then solved as an inverse problem. We present the state of the art, focusing on the statistical and systematic effects affecting the final results, which are probed both for (analytic) test functions, and for lattice QCD data (obtained by the Bielefeld-Parma collaboration). We will show the analytic continuation of the $N_f=2+1$ net baryon-number density at physical quark mass. Higher-order cumulants evaluated at $\mu=0$ will be presented and compared to the ones already published in the literature. A new estimate for the 10th order cumulant will also be provided.

Speaker: Marco Aliberti (University of Parma & INFN)

15:00 Comparison of various extrapolation schemes for the equation of state at finite density

Contour-based extrapolation of thermodynamic observables to finite chemical potential is known to overcome the shortcomings of Taylor series extrapolation and to extend the reach in the finite density region. Two such schemes are the T-prime expansion, which uses contours of constant baryon density, and a recently proposed scheme using contours of constant entropy. However, a detailed comparison of these schemes has not yet been performed. Using large-statistics data on a $16^3 \times 8$ lattice, we push these expansions to higher orders than those explored in the original works. One of the difficulties in doing so is the accurate computation of higher-order temperature derivatives of the defining observables, namely baryon density and the entropy density. To this end, we employ a Bayesian approach to spline fitting with free knots to obtain the required derivatives. In this talk, we present a systematic comparison of the two schemes to assess their relative performance for future extrapolation studies.

Speaker: Piyush Kumar (Bergische Universität Wuppertal)

15:20 Alleviating the sign problem with contour deformations in heavy-dense QCD

We investigate contour deformation strategies for alleviating the finite-density sign problem in the heavy-dense limit of QCD in two, three, and four dimensions. To reduce the number of integration variables, we work in Polyakov gauge and consider complex deformations of the Polyakov loop eigenvalues. We study approaches based on holomorphic flow equations as well as numerical optimization, using the average phase as the primary diagnostic for the severity of the sign problem. We find that both approaches can considerably alleviate the sign problem in heavy-dense QCD.

Speaker: Emmanuel Ortiz Pacheco (Eötvös Loránd University)

14:00 → 15:40 Quantum computing and quantum information

14:00 Fuzzy regularization of Hamiltonian $\mathrm{CP}^N$ models

Simulations of quantum many-body systems based on the Hamiltonian formulation are emerging as a new tool to study phenomena inaccessible with traditional methods. A significant challenge is encoding physical systems in the Hamiltonian formulation, particularly achieving a finite Hilbert space which still accommodates the relevant physics. It has been shown that fuzzy regularization allows one to recover continuum physics for bosonic systems even with a finite Hilbert space per site. In this talk I will introduce a fuzzy-regularized Hamiltonian for $\mathrm{CP}^N$ models, discuss its equivalence with a generalized Heisenberg comb construction, and show results on the mass gap, the entanglement entropy, and the step-scaling function of the $\mathrm{CP}^2$ theory.

Speaker: Andrea Bulgarelli (University of Bonn)

14:20 Towards the Mass Shift and Discrete Chiral Symmetry in the Lattice QED Hamiltonian

We study the lattice Hamiltonian formulation of quantum electrodynamics with staggered fermions and extend the mass-shift construction developed for the Schwinger model to the $(3+1)$-dimensional case. In the Schwinger model, the chiral transformation is realized as a one-site translation of the staggered fermion field. By introducing a correction term, referred to as the mass shift, the lattice Hamiltonian possesses an exact discrete chiral symmetry, while also allowing for the correct transformation of the $\theta$ parameter, leading to significantly improved convergence of numerical calculations.

In this work, we generalize this construction to $(3+1)$-dimensions and show that the resulting lattice Hamiltonian with the mass shift also possesses an exact discrete chiral symmetry. The realization of the $\theta$ parameter shift is left for future work.

Speaker: Shoto Aoki (RIKEN iTHEMS)

14:40 A Finite-Volume Scheme for the Continuum Extrapolation of Lattice Step-Scaling in (2+1)D Hamiltonian U(1) Gauge Theory

We propose a finite-volume scheme to perform controlled continuum extrapolations of the lattice step-scaling function, a key ingredient for determining the running coupling in a Hamiltonian lattice gauge theory in small volumes. As a testbed, we employ a dual Hamiltonian formulation of pure U(1) gauge theory in (2+1) dimensions and an operator basis that remains efficient toward weak coupling. We describe the implementation of static external charges on the spatial lattice and study, using matrix product states, the resulting confining string, from which we extract the static potential and a force-based renormalized coupling. Using the proposed finite-volume scheme, we demonstrate a stable continuum limit of the step-scaling function on the lattice sizes accessible to present Hamiltonian simulations. The method is readily extendable to other gauge groups and dimensions, providing a pathway toward Hamiltonian step-scaling studies in other theories.

Speaker: Alessio Negro (University of Bonn, HISKP)

15:00 Obtaining continuum physics from dynamical simulations of Hamiltonian lattice gauge theories

Taking the continuum limit is essential for extracting physical observables from quantum simulations of lattice gauge theories. Achieving this limit requires careful control of all systematic uncertainties, including those from approximate time evolution. Existing methods for product formulas rely on complicated renormalization trajectories because of the dependence on both the lattice spacing and renormalized Trotter step-size. More fundamentally, no analogous method exists for the myriad other simulation algorithms, making systematic and fair cost comparisons impossible. This work addresses both problems. For product formulas, we show that Trotter errors are irrelevant operators that vanish in the continuum limit, allowing us to introduce a simplified renormalization trajectory independent of the Trotter step-size. To address the general case, we then present the Statistically-Bounded Time Evolution (SBTE) protocol, a new framework for applicable to any simulation algorithm. The central insight is that, since exact evolution introduces no UV divergences, approximation errors can be treated as a systematic uncertainty that must be driven below the working statistical uncertainty. This not only simplifies renormalization but, due to existing rigorous error bounds, provides an a priori guarantee that such errors do not affect the continuum limit. Ultimately, our protocol provides the first rigorous foundation for performing fair cost comparisons of taking the continuum limit between different simulation algorithms.

Speaker: Christopher Kane (University of Maryland)

15:20 Confinement and String Breaking in the Compact Abelian Higgs Model

While real-time simulation of Quantum Chromodynamics remains technologically out of reach, simplified models for studying elements of QCD phenomenology abound. This work aims to add a spin-1 truncation of 1+1D scalar electrodynamics represented on a chain of qutrit sites to the collection of models considered to demonstrate confinement and string breaking accessible to current simulation methods. We study the spectrum of the effective string model using DMRG methods on the order of 100 sites. We demonstrate that an added chemical potential, playing a role analogous to external charges, permits parameter-dependent measurements of physical features of interest like the string tension and effective meson mass. Varying the chemical potential also permits a characterization of string stability not assessed in prior studies of confining lattice models.

Speaker: Blake Senseman (University of Iowa)

14:00 → 15:40 Quark and lepton flavor physics

Convener: Masaaki Tomii

14:00 Comparing single-hadron and multi-hadron treatments of a narrow $\rho$ in $B\to\rho\ell\bar{\nu}$

We compare multi-hadron and single-hadron treatments of $B\to\rho\ell\bar{\nu}$ in lattice QCD using one $N_f=2+1$ clover-Wilson ensemble with $m_\pi \approx 320$ MeV, where the $\rho$ has a decay width of approximately $40$ MeV. In the multi-hadron analysis, the unstable $\rho$ is treated as an interacting $I=1$, $P$-wave $\pi\pi$ final state with the full use of the finite-volume formalism. In contrast, the stable-$\rho$ analysis assumes that the state produced with a $\bar{q}\gamma_\mu q$ interpolator at an intermediate Euclidean-time-distance is the correct state and determines the form factors from its matrix elements. The single-hadron treatment reproduces the qualitative $q^2$ dependence but slightly shifts some form factors (statistically significantly).

Speaker: Luka Leskovec (Jozef Stefan Institute & Faculty of Mathematics and Physics, University of Ljubljana)

14:20 $B_s \to K\ell\nu$ semileptonic form factors from lattice QCD with domain-wall heavy quarks

We report on our on-going study of the $B_s \to K\ell\nu$ semileptonic decays in $N_f = 2 + 1$ lattice QCD. Our simulations are carried out at a lattice cut-off $a^{-1} \sim 2.5$ GeV and a pion mass $M_\pi \sim 500$ MeV. The Mobius domain-wall action is employed for all quark flavors with bottom quark masses up to $m_b < 0.7 a^{-1}$ to control discretization errors. We present our preliminary results for relevant form factors, and discuss the systematic uncertainties associated with different treatments of excited state contribution.

Speaker: Junya Tokoro (The University of Osaka)

14:40 Update on $B_s \to K \ell\nu$ and $B \to \pi \ell\nu$ semileptonic decay form factors from the ALPHA Collaboration

We present an update on our determination of the $B_s \to K$ and $B \to \pi$ semileptonic decay form factors. The ALPHA Collaboration aims to compute these form factors by interpolating continuum-limit observables in $1/m_h$, constructed so that the matching and renormalisation cancel. Relativistic continuum data at and above the charm mass are interpolated with their static-limit counterparts. This talk concentrates on the relativistic data obtained on CLS ensembles. Using five lattice spacings, down to $a \approx 0.04 \text{ fm}$, we investigate the continuum-limit extrapolation at the $\mathrm{SU}(3)$-symmetric point ($m_\pi = m_K \approx 420 \text{ MeV}$). Furthermore, at a fixed fine lattice spacing, $a \approx 0.05 \text{ fm}$, we explore the approach to the physical pion mass, where multi-particle excited-state contributions -- in particular $B^{*}\pi$ -- become increasingly significant for $B \to \pi$. Systematic effects in the extraction of the ground-state matrix elements at finite Euclidean time are reduced by employing summed ratios, together with a heavy-meson-ChPT-guided model treatment of the $B^{*}\pi$ excited-state contributions.

Speaker: Antonino D'anna (INSTITUTO DE FISICA TEORICA, UAM-CSIC)

15:00 $B \to \pi \ell \nu$ from lattice QCD using $n_f=2+1+1$ HISQ

We present an update on our calculation of form factors for the decay $B\to \pi \ell \nu$ from lattice QCD using Highly Improved Staggered Quarks. The calculation is performed using the MILC collaboration's $n_f = 2+1+1$ HISQ gauge-field ensembles with the same HISQ action used for both the valence and sea quarks. We use nine ensembles with lattice spacings ranging from 0.09 fm down to 0.03 fm. Three ensembles have physical mass pions, and on the three finest ensembles we compute form factors at the physical bottom quark mass. In this talk, we present preliminary, blinded results of our form factors in the continuum limit at the physical point.

Speaker: Nicholas Cassar (Colorado State University)

15:20 Progress on bottom-baryon decay form factors from lattice QCD

I will present a lattice calculation of $\Xi_b \to \Xi$ form factors with application to rare decays, and give an update on my progress toward improved determinations of the $\Lambda_b \to p$, $\Lambda_b \to \Lambda$, and $\Lambda_b \to \Lambda_c$ form factors. An important methodological advance is the use of modified $z$ expansions that include dispersive bounds and asymptotic-behavior constraints to achieve controlled uncertainties in the full kinematic range.

Speaker: Prof. Stefan Meinel (University of Arizona)

14:00 → 15:40 Structure of hadrons and nuclei

Convener: Joseph Karpie

14:00 Decomposition of the nucleon spin and gravitational form factors in the continuum limit directly at physical pion mass

We determine the complete spin and momentum fraction decomposition of the nucleon at the continuum limit and compare with phenomenological analyses.
The computation is done using four twisted mass ensembles with different lattice spacings and physical pion mass.
The renormalization functions are computed fully non-perturbatively including the mixing between the singlet quark and gluon operators.
In addition, we present preliminary results on the gravitational form factors as a function of the momentum transfer square for the same ensembles.

Speaker: Constantia Alexandrou

14:20 The axial structure of the nucleon with the PACS10 superfine lattice

This study uses the third PACS10 gauge ensemble generated by the PACS Collaboration, providing a large physical volume exceeding $(10\,\mathrm{fm})^4$. This large volume is highly advantageous for determining detailed form factors in the small-$q^2$ region, where the root-mean-square radius, i.e., the axial radius, can be more precisely evaluated. The resulting nucleon axial-vector form factor can contribute to reducing uncertainties in neutrino oscillation experiments. While our results for the axial-vector form factor at two lattice spacings—0.085 fm (coarse) and 0.063 fm (fine)—have already been published, calculations at a third lattice spacing of 0.041 fm (superfine) are currently in progress. In this talk, we present recent updates on the axial form factor and the axial radius obtained from the superfine lattice configurations, which allows us to investigate systematic uncertainties, such as discretization errors.

Speaker: Masato Nagatsuka (Tohoku University)

14:40 Nucleon Electromagnetic Form Factors at the Physical Pion Mass from PNDME Collaboration

Results from ongoing calculations of the nucleon isovector electromagnetic form factors by the PNDME collaboration are presented. These are based on data from $\mathcal{O}(7000)$ configurations on two physical pion mass ensembles with $2+1+1$-flavor HISQ generated by the MILC collaboration at lattice spacings $a=0.087$ and $a=0.0576$ fm. We will discuss the extraction of the electric and magnetic form factors, focusing on the systematic improvements in the removal of excited-state contributions and the analysis of their $Q^2$ behavior.

Speaker: Sungwoo Park (Sejong University)

15:00 Nucleon electromagnetic form factors at large momentum from Lattice QCD

Proton and neutron electric and magnetic form factors are the primary characteristics of their spatial structure and have been studied extensively over the past half-century. At large values of the momentum transfer $Q^2$ they should reveal transition from nonperturbative to perturbative QCD dynamics and effects of quark orbital angular momenta and diquark correlations. Currently, these form factors are being measured at JLab at momentum transfer up to $Q^2=18$ GeV$^2$ for the proton and up to 14 GeV$^2$ for the neutron. We will report an updated calculation of these form factors using nonperturbative QCD on the lattice, including $G_E$ and $G_M$ nucleon form factors with momenta up to $Q^2=12$ GeV$^2$, pion masses down to the almost-physical $m_\pi$=170 MeV, several lattice spacings down to $a=0.073$ fm, and high $O(10^5)$ statistics. Specifically, we study the $G_E/G_M$ ratios, asymptotic behavior of the $F_2/F_1$ ratios, and flavor dependence of contributions to the form factors. We observe some qualitative agreement of our ab initio theory calculations with experiment. Comparison of our calculations and upcoming JLab experimental results will be an important test of nonperturbative QCD methods in the almost-perturbative regime.

Speaker: Prof. Sergey Syritsyn (Stony Brook University)

15:20 Optimised Distillation for Nucleon Correlation Functions

The calculation and analysis of nucleon correlation functions is essential for understanding the observed spectra and structure of these ubiquitous hadrons. Two challenges arise in their analysis: at early Euclidean times, they are dominated by excited state contributions, and at later Euclidean times, the signal-to-noise ratio is too great to extract meaningful physics. This leads to a common challenge in identifying a reasonable window on which to extract the ground state energy. By modulating the contribution of each Laplacian eigenmode to the correlator via "distillation profiles," we build optimised operators which improve the overlap with the nucleon ground state. In this talk, we present our preliminary work on constructing these optimised distillation profiles for nucleons and their excited state suppression in two- and three-point correlation functions.

Speaker: Joshua Crawford (University of Wuppertal)

14:00 → 15:40 Theoretical developments and applications beyond the SM

Convener: Hersh Singh (Fermilab)

14:00 Tensor renormalization group approach to entanglement negativity

Entanglement negativity is a measure of quantum entanglement and defined as the trace norm of the partially transposed density matrix. One of the important properties of entanglement negativity is that it can be used to quantify the amount of entanglement in mixed states. We represent the density matrix of a 1D quantum system as a 2D tensor network and calculate the entanglement negativity using the tensor renormalization group method. We investigate the temperature dependence of entanglement negativity in the 1D transverse field Ising model and show that the result agrees with the known result.

Speaker: Gota Tanaka (Meiji Gakuin University)

14:20 Probing Criticality in the (1+1)D Real Scalar $\phi^4$ Theory with Entanglement Entropy and HOTRG

Entanglement entropy (EE) is a measure of quantum entanglement and provides a powerful probe of critical behavior. In particular, an effective central charge can be extracted from the EE and is expected to provide valuable information about criticality. We compute the EE in the (1+1)-dimensional real scalar $\phi^4$ theory using the higher-order tensor renormalization group (HOTRG) method. We then investigate whether the effective central charge can be used to identify the critical point of the theory.

Speaker: Takahiro Hayazaki (Kanazawa University)

14:40 Tensor Renormalization Group Study of Step-Scaling Function in the CP(1) Model with a $\theta$ Term

The step-scaling function (SSF) is a non-perturbative tool to determine the running coupling in lattice gauge theory.
The tensor renormalization group (TRG), which is free from the sign problem, allows us calculate the SSF in the CP(1) model with a $\theta$ term. We first study the $\theta = 0$ case to validate the calculation of the SSF with the TRG method comparing our results with the previous Monte Carlo ones.
We then extend the analysis to the $\theta = \pi$ case, where the running coupling obtained with the SSF indicates the existence of a infrared conformality.

Speaker: Hayato Aizawa (University of Tsukuba)

15:00 Tensor renormalization group study of cold and dense two- and three-color QCD in the strong coupling limit

We investigate the phase structure of two- and three-color QCD in the strong coupling limit using the tensor renormalization group method. By analytically integrating out the gauge fields, the partition function can be represented as a Grassmann tensor network. Applying the tensor renormalization group method to the network allows us to directly calculate partition functions in the cold and dense regime, even for the three-color case, where the sign problem is present. At zero temperature, we calculate physical quantities such as the quark number density, chiral condensate, and diquark condensate. We also apply the method to the finite-temperature regime in the three-color case and determine the location of the critical endpoint associated with the chiral and nuclear phase transitions.

Speaker: Yuto Sugimoto (Tohoku University)

15:20 Phase diagram of the single-flavor Gross–Neveu–Wilson model from the Grassmann corner transfer matrix renormalization group

We investigate the phase structure of the (1+1)-dimensional single-flavor Gross–Neveu model with Wilson fermions using the Grassmann corner transfer matrix renormalization group (CTMRG). The path integral is formulated as a two-dimensional Grassmann tensor network and approximately contracted by the Grassmann CTMRG algorithm. We investigate the phase diagram by varying the fermion mass and the four-fermion coupling, using the pseudoscalar condensate as an order parameter for the $\mathbb{Z}_{2}$ parity symmetry breaking phase. The universality classes of the phase boundaries are identified through the central charge $c$ obtained via scaling analysis of the entanglement entropy. Furthermore, we extract the quantity related to the entanglement spectrum from the converged CTMRG environments, allowing us to distinguish the topological insulator phase and the trivial phase. The resulting phase structure suggests that the Aoki phase is separated from the other phases by critical lines characterized by $c=1/2$, while the critical lines with $c=1$ separate the topological insulating and trivial phases. Our numerical results also indicate that the Aoki phase does not persist in the strong-coupling regime for the single-flavor theory.

Speaker: Shinichiro Akiyama (University of Tsukuba)

15:40 → 16:10 Coffee break

16:10 → 17:30 Algorithms and artificial intelligence

Convener: Francesco Di Renzo (University of Parma and INFN)

16:10 Diagonalizing the Kogut-Susskind Hamiltonian with Physics-Informed Neural Networks

The Hamiltonian formulation of lattice gauge theories solves several of the problems in Euclidean Monte Carlo simulations. However, the main obstacle is the exponential growth of the Hilbert space with the lattice volume, and one needs to find an effective representation that fits the computer memory. Most of the present calculations rely on explicit truncation methods, usually suited only for a fixed region of the coupling. In this talk I present a new approach based on Physics-Informed Neural Networks (PINNs), where the wavefunction is parametrised by a neural network and the eigenvalue problem is encoded in the loss function. By training at progressively weaker couplings, PINNs allow to move along the renormalization flow of the theory. This is achieved using an adiabatic training strategy, seeded from the analytically known strong-coupling eigenstates.

Speaker: Simone Romiti

main.pdf

16:30 Neural Wavefunctions in Quantum Field Theory

We present a variational approach to quantum field theory based on wavefunctions parameterized by neural networks, as a stepping stone towards real-time and finite-density regimes, inaccessible to path-integral Monte Carlo. Working in the Hamiltonian formulation on a spatial lattice, we optimize a neural-network ansatz with variational Monte Carlo to obtain the ground-state and excited-state wavefunctions. As a proof of principle, we study the 1+1d nonlinear sigma model and reproduce its essential features: asymptotic freedom, dynamical mass generation, and the model's step-scaling curve. Although energy minimization is dominated by short-distance modes, the trained wavefunction nonetheless captures long-distance physics.

Speaker: Suryansh Rajawat (University of Maryland)

16:50 3+1d SU(3) Yang-Mills + theta-term with Neural Network Quantum States

In the Euclidean path-integral formalism, the theta-term introduces a sign problem which makes direct investigation difficult. On the other hand, the theta-term can be included in a Hamiltonian formulation straightforwardly - as long as one can deal with the infinite dimensional Hilbert space. In this contribution we present an investigation into the 3+1d SU(3) Yang Mills action with nonzero theta-term using Neural Network quantum states.

Speaker: Joshua Lin (Argonne National Laboratory)

17:10 The Affine Conjecture: Using Numerical Methods to Tune Geometries for Non-integrable Lattice Field Theories

Placing lattice field theories on curved spacetimes requires more than a choice of triangulation: the UV couplings must encode the real-space geometry seen by long-distance observables. Motivated by Brower and Owen's solution for the 2D Ising model on a latticized two-sphere [arXiv:2407.00459], the affine-plane Ising construction [arXiv:2209.15546] and the affine conjecture [arXiv:2503.05621], we develop a numerical method for determining this coupling-geometry map for non-integrable models. In a 2D Ising testbed, we construct the map empirically by matching reweighted critical correlators between boundary-deformed and coupling-deformed lattices. The recovered map agrees with the known affine geometry structure within current uncertainties, supporting the method as a bridge to non-integrable curved-space lattice field theory. The target application is the critical 3D Ising model on R x S2, where radial quantization would allow direct comparison of conformal data with conformal bootstrap and fuzzy-sphere calculations. Future applications include gauge theories on R x S2, including QED3 [arXiv:2510.03085], and four-dimensional gauge theories on R x S3.

Speaker: Rohan Misra (Boston University)

16:10 → 17:30 Hadronic and nuclear spectrum and interactions

Convener: Sinya Aoki

16:10 Diquarks properties from heavy-light tetraquark operators

Diquarks are colour-nonsinglet objects that have gained interest in the study of baryons, tetraquarks and other exotics. A gauge invariant way of measuring diquark properties is obtained by contracting all colour indices with static colour sources. We extend this approach from baryons to tetraquarks with two static and two light quarks, which allows directly probing diquarks in higher colour representations on the lattice. We derive the structure of all Wick diagrams involved for an arbitrary number $N_f$ of light quarks and colours $N_c$ from tetraquark operators informed by the Born-Oppenheimer Effective Field Theory (BOEFT) and set the stage for first-principles calculation on the lattice.

Speaker: Fabian Zierler (Technical University of Munich)

16:30 Update on lattice study of $T_{cc}^+$ using three-body formalism

I present an update on our ongoing study of the $T_{cc}^+$, based on two CLS ensembles (X252 and X253) for which $M_\pi\approx 280\,$MeV. We have determined the spectra for $DD\pi$ ($I=0$), as well as the subchannels $DD$ ($I=1$) and $D\pi$ ($I=1/2$), using a range of operators in several frames and irreps. We fit these using a combination of two- and three-particle quantization conditions, with the primary aim being a determination of properties of the $DD^*$ system. The lightest $DD^*$ states lie below the $DD^*$ left-hand cut due to $u$-channel pion exchange, and thus cannot be described by the Luscher version of the two-particle quantization. The three-particle formalism incorporates the pion exchange, and we present the present status of our results using this methodology.

Speaker: Stephen Sharpe (University of Washington)

sharpe_lat26.pdf

16:50 Deeply bound $T_{bb}$ and near-threshold $BB^*$ scattering with a relativistic heavy quark action

The doubly bottom tetraquark $T_{bb}$, with $I(J^P) = 0(1^+)$, is widely expected to be a deeply bound exotic state. In contrast, much less is known about $BB^*$ scattering near and above threshold. Studying this system is challenging: one must separate the deeply bound $T_{bb}$ from the $B^{(*)}B^*$ scattering states by using both local tetraquark operators and bilocal scattering operators. In this exploratory study, we employed a relativistic heavy quark (RHQ) action for the $b$ quark on two CLS ensembles with Wilson-clover fermions at the $SU(3)$-flavour-symmetric point. To include both operator types in the variational analysis, we used the distillation framework combined with a position-space sampling method [arXiv:2510.26459]. In our preliminary analysis, we find a binding energy of about 50–60 MeV for the $T_{bb}$, consistent with the literature. We further determine the $s$-wave $BB^*$ scattering phase shift using Lüscher's finite-volume quantization conditions. The scattering amplitude from our single-channel analysis contains a pole close to threshold, indicating a shallow virtual bound state alongside the deeply bound $T_{bb}$.

Speaker: Andres Stump (Humboldt-Universität zu Berlin)

17:10 Static energies in the $Z_b$ tetraquark channel using novel BOEFT interpolators

We study the $Z_b$ tetraquark channel, $\bar{b}b\bar{d}u$, with quantum numbers $J^{PC}=1^{+-}$. Our approach involves calculating correlators among three operator classes: (i) static-light meson pair, (ii) quarkonium plus pion, and (iii) the novel interpolator based on BOEFT (Born–Oppenheimer Effective Field Theory) proposed in Ref. [1]. We use the GEVP variational approach to extract the preliminary eigenenergies and overlap factors from the correlation matrix. At short distances, at leading order, this novel interpolator has zero overlap with quarkonium and pions due to the $Q\bar{Q}$ pair being in a color-octet configuration. In contrast, at large distances it evolves into a static-light meson pair, making it a suitable choice to calculate the tetraquark static energies on the lattice. To achieve this, we employ the distillation technique on a CLS ensemble with $N_f=2+1$ and $m_{\pi}=290$ MeV.

[1] Matthias Berwein, Nora Brambilla, Abhishek Mohapatra, and Antonio Vairo. Hybrids, tetraquarks, pentaquarks, doubly heavy baryons, and quarkonia in Born–Oppenheimer effective theory. Phys. Rev. D 110(9):094040, 2024.

Speaker: Sipaz Sharma (Technical University Munich)

16:10 → 17:30 QCD at nonzero temperature and density

Convener: Jana N. Guenther (University of Wuppertal)

16:10 Finite temperature gluon propagator in the center-symmetric Landau gauge

The lattice gluon propagator at finite temperature is computed in the recently introduced center-symmetric Landau gauge in pure Yang-Mills theory. Recent works in the continuum, e.g. [1] show that the gluon propagator is degenerate along the diagonal color directions in the confining phase, and becomes nondegenerate in the deconfined phase. This result allows to use the gluon propagator to define order parameters for the deconfinement phase transition, alongside the well-known Polyakov loop. After discussing a proper lattice implementation of the center-symmetric Landau gauge [2], lattice data for the gluon propagator is shown and compared with continuum studies predictions. Other signatures of the breaking of the center symmetry are also investigated.

[1] D. M. van Egmond, U. Reinosa, Phys. Rev. D106 (2022) 074005 [arXiv:2206.03841 [hep-ph]].
[2] D. M. van Egmond, O. Oliveira, Urko Reinosa, Julien Serreau, Paulo J. Silva, Matthieu Tissier, Phys.Rev.D 112 (2025) 1, 014512 [arXiv:2412.07930 [hep-lat]].

Speaker: Paulo Silva

16:30 Study of the thermodynamics of QCD+QED from the lattice

QED corrections to observables in QCD are by now well-understood at zero temperature, where QED effects are perturbative and are required for precision physics observables, such as the neutron-proton mass difference or the muon g-2, among many others. However, there are indications that at finite temperature the introduction of QED can lead to non-perturbative effects, affecting the structure of the phase diagram, since the combined theory is exactly center-symmetric. In this talk, we will analyze the structure of the combined theory and the different strategies to simulate it on the lattice. We will continue by presenting novel results of lattice QCD+QED simulations at finite temperature, focusing on understanding the role of the electromagnetic coupling in the thermodynamics of this system. We will also discuss new features that arise in the combined theory and the challenges that these simulations entail, as well as the new directions we are currently developing to understand the phase diagram of QCD+QED from first principles.

Speaker: Eduardo Garnacho-Velasco (Eotvos Lorand University)

16:50 Leading-order dynamical QED corrections to the thermodynamics of isospin-asymmetric QCD

At large isospin chemical potential $\mu_I$ and low temperature, QCD undergoes a second-order transition to a Bose-Einstein condensate of charged pions, whose order is encoded in the non-analytic $\mu_I$-dependence of the pressure and of the isospin density derived from it. Including dynamical photons is expected, on general grounds, to drive this transition first order. Since unequal quark charges render the QCD+QED action complex, we avoid the sign problem by expanding the pressure to $\mathcal{O}(e^2)$ around $e=0$, with the leading contribution governed by the second charge-derivative of the free energy density, $\partial^2 f/\partial e^2|_{e=0}$. We evaluate it directly on existing isospin-asymmetric pure-QCD ensembles as a spacetime convolution of the Feynman-gauge photon propagator with the vector current-current correlator at nonzero $\mu_I$ and pion source $\lambda$. The full correlator is computed using a point source and a newly proposed two-dimensional planar source. We report progress toward the first lattice determination of $\partial^2 f/\partial e^2|_{e=0}$ as a function of $\mu_I$, which captures, at leading order, the imprint of dynamical photons on the thermodynamics across the transition.

Speaker: Mr Gergely Marko (Eotvos Lorand University, Institute of Physics)

17:10 Chemical potential dependence of hadron masses in two-color QCD

We investigate the chemical-potential dependence of hadron masses in two-color QCD (QC$_2$D) using first-principles lattice simulations. QC$_2$D provides a useful theoretical laboratory for studying cold dense QCD matter, since it is free from the sign problem while sharing several important nonperturbative features with three-color QCD. In this work, we compute two-point correlation functions for all allowed hadronic operators, newly including contributions from disconnected diagrams, and extract the corresponding effective masses at finite quark chemical potential.
In the meson sector, we find that the mass hierarchy in the hadronic phase is qualitatively similar to that in three-color QCD, while it is substantially modified after the onset of the superfluid phase. In the diquark sector, the Nambu--Goldstone mode associated with the spontaneous breaking of U(1)_B is confirmed to be nearly massless, and the ordering of the diquark spectrum remains relatively stable across the transition. We also compare correlators of chiral partners and find indications of chiral symmetry restoration at high density.
Our results provide a systematic view of how hadronic excitations evolve from the normal vacuum to dense superfluid matter in QC$_2$D, and offer useful benchmarks for effective theories of dense QCD-like matter.
This talk is based on arXiv:2606.13974.

Speaker: Etsuko Itou

16:10 → 17:30 Quantum computing and quantum information

Convener: Christopher Kane (University of Maryland)

16:10 Simulating (3+1)D SU(2) Hamiltonian lattice gauge theory with a topological $\theta$-term

We present a numerical study of the topological $\theta$-term in (3+1)D pure SU(2) Yang-Mills theory in a sign-problem-free Hamiltonian lattice formulation, using exact diagonalization on a single periodic cube and minimal field truncation. In the strong-coupling regime, we uncover distinct $\theta$-dependent phases, signaled by peaks in the topological susceptibility, and sharp variations in the plaquette expectation value, electric energy, and topological charge. We also analyze the entanglement entropy to assess prospects for tensor-network and quantum-computing studies at larger lattice volumes.

Speaker: Lena Funcke (University of Bonn)

16:30 A Path to Quantum Simulations of (3+1)D U(1) Gauge Theory with a Topological $\theta$-Term

While Monte-Carlo-based simulations of lattice gauge theories have been remarkably successful across a wide range of applications, they typically break down in physical settings afflicted by the sign problem. One possible path for circumventing the sign problem is quantum simulation, which have shown substantial progress in the last years in simulating $(1+1)$- and $(2+1)$-dimensional theories. To date, however, these efforts have not been extended to $(3+1)$D theories exhibiting a sign problem. We present a path toward the simulation of $(3+1)$D U(1) lattice gauge theory with a topological $\theta$-term. Using an efficient mapping to a qudit quantum device, we estimate the resources needed for simulating a $2\times2\times2$ cube with periodic boundary conditions. Additionally, we discuss simplifications to the theory, offering a reduction of the potential gate depth while preserving the physically interesting properties of the theory.

Speaker: Emil Otis Rosanowski

16:50 Quantum Simulations of Topological Phases: (2+1)D Lattice QED with Wilson Fermions

We present results on quantum simulations of topological phases in $(2+1)$D lattice QED with one and two fermion flavors, at both zero and finite density. Establishing that staggered fermions fail to host infrared topological phases, we show that Wilson fermions give rise to Chern-Simons physics in the infrared, reflecting consistency with both the lattice Lagrangian and the continuum formulations. We analyze the topological phase diagram as a function of the fermion masses and couplings for both $N_f=1$, and then $N_f=2$ at finite density which is affected by the sign problem. For the $N_f=2$ theory, we uncover a rich phase diagram, containing regimes that exhibit Integer Quantum Hall and Quantum Spin Hall effects. We analytically prove the robustness of topological observables such as Chern numbers and current correlators despite severe truncation and finite-size effects, making them ideal targets for quantum simulation. Finally, through extensive exact diagonalization calculations for both $N_f=1$ and $N_f=2$, we characterize the spectrum, correlators, and topological invariants, providing a concrete foundation for near-term quantum simulations of topological phases in lattice field theories. We close by outline concrete implementation strategies employed for simulation on superconducting quantum hardware. The talk will be based on https://arxiv.org/pdf/2603.05616 and https://arxiv.org/pdf/2504.21828, and ongoing work.

Speaker: Sriram Bharadwaj (University of California, Los Angeles (UCLA))

17:10 Finite Size Scaling of Probability Distributions

In the current landscape of quantum computation, estimating necessary shot totals for desired accuracy is a preeminent question. Here, we introduce the usage of cumulative probability distributions: sums of total probability up to a capped value, working through the entire probability spectrum. These cumulative distributions of Rydberg atom arrays are approximated well by Fermi distributions, permitting the collapse of the cumulative distributions across increasing system sizes given their fitting. Using these, we are also able to determine how overall features of the probability distribution scale with system size, providing insight to predict large scale behavior from limited sample data in smaller systems. We will also discuss the applicability of these analysis methods to operators and highlight the potential for extension to other quantum models.

Speaker: Zane Ozzello

16:10 → 17:30 Quark and lepton flavor physics

Convener: Oliver Witzel (University of Siegen)

16:10 Gauge-invariant renormalization of $\Delta F=1$ four-quark operators

We study the renormalization of $\Delta F=1$ four-quark operators in a gauge-invariant renormalization scheme (GIRS). We begin by classifying a complete basis of scalar and pseudoscalar four-quark operators into irreducible representations of the flavor symmetry group and analysing their symmetry properties and mixing patterns. We then consider all classes of $\Delta F=1$ operators, including those that can mix with lower-dimensional operators. To determine the full operator mixing set in the latter case, we further investigate relevant spurionic symmetries on the lattice. Our calculations are performed in both continuum and lattice perturbation theory, employing Osterwalder-Seiler fermions in the lattice regularization. We formulate and explore a wide range of GIRS variants and identify those with reduced mixing effects. For selected promising variants, we present next-to-leading order results for the conversion matrices to the $\overline{\rm MS}$ scheme.

Speaker: Dr Gregoris Spanoudes (University of Cyprus)

16:30 Continuum and chiral extrapolations in the lattice calculation of inclusive $D_s$-meson semileptonic decays

We report on recent progress in the calculation of inclusive semileptonic decay rates for $D_s$ mesons from lattice QCD. In this talk, we present results on the continuum and chiral extrapolations performed using gauge ensembles generated with 2+1 flavors of Möbius domain-wall fermions. We obtain results that are in agreement with currently available experimental data, with an error at the few-percent level.

Speaker: Ryan Kellermann (High Energy Accelerator Research Organization (KEK))

16:50 Precision determination of $B_c$ and $B_c^\star$ meson decay constants from lattice QCD

We present a lattice QCD study of heavy-heavy meson decay constants using HISQ gauge ensemble generated by the MILC Collaboration. Employing the HISQ action for both charm and bottom valence quarks tuned to their physical masses, we determine pseudoscalar, vector, and tensor decay constants for heavy quarkonium and $B_c$ systems. Preliminary results are presented for the decay constants of the $B_c$, $B_c^\star$, $\eta_c$, $\eta_b$, and $\Upsilon$ mesons.

Speaker: Navdeep Singh Dhindsa (TIFR Mumbai)

17:10 $B_{(s)} \to D_{(s)} \ell \nu$ with Highly Improved Staggered Quarks

We present a calculation of the form factors for $B_{(s)} \to D_{(s)} \ell \nu$ decay using the highly improved staggered quark action for both valence and sea quarks on the MILC collaboration’s $2+1+1$-flavor ensembles. We use 9 ensembles with lattice spacings ranging from 0.09fm to 0.03fm, 3 of which have physical pion masses. On our finest ensembles, we compute the form factors directly at the physical $b$-quark mass. In this talk, we present blinded results of our form factors in the continuum limit at the physical point. We present error budgets including statistical and systematic errors. For $B \to D$ we combine our results with experimental data to obtain blinded results for $|V_{cb}|$ and $R(D)$.

Speaker: Akhil Chauhan (University of Illinois Urbana Champaign)

16:10 → 17:30 Structure of hadrons and nuclei

Convener: Christian Zimmermann (University of Kentucky)

16:10 Nucleon sigma terms at $m_\pi=222$ MeV with a variational analysis from lattice QCD

Nucleon sigma terms are important for the decomposition of the nucleon mass and for searches for new physics beyond the Standard Model involving scalar interactions. A persistent tension between lattice QCD and phenomenological determinations may be due to uncontrolled excited-state contamination in lattice QCD analyses. In previous work at $m_\pi=429$ MeV, we showed that this contamination is dominated by $N\sigma$ states and can be strongly suppressed with a $2\times 2$ variational analysis using $N$ and $N\sigma$ operators. In this talk, we present preliminary results at $m_\pi=222$ MeV, where the $\sigma$ becomes unstable and decays into $\pi\pi$. We investigate whether the same small variational basis can remove the expected $N\pi\pi$ contamination through the overlap of the $N\sigma$ operator with these states.

Speaker: Lorenzo Barca (DESY)

16:30 Direct Determination of the Sigma Terms of the Baryon Octet from $N_\mathrm{f} = 2+1$ Lattice QCD with Wilson fermions

Sigma terms are of fundamental interest as measures of the quark mass contributions to the mass of a given baryon. As the key input for neutrino and nucleon cross-sections, the nucleon sigma terms are relevant for dark matter predictions. Further, for the nucleon-pion sigma a long standing discrepancy between Lattice QCD and phenomenology persists. By performing a direct determination of the full baryon octet for the first time in a combined analysis on 34 CLS ensembles, we provide new insight into this disparity. I will present how we tackle the excited state contamination; we investigate the effect of different multi-state fits on the sigma terms and assess systematics. The baryon octet sigma terms are then simultaneously extrapolated to the physical point taking the quark mass dependence, lattice spacing and finite volume effects into account. I will conclude by discussing the final steps to work out the error budget in detail, including model averaging.

Speaker: Pia Leonie Jones Petrak (JLab)

16:50 Accessing Nucleon Sigma terms with Gradient Flow

Nucleon sigma terms quantify the contributions of scalar quark condensates towards the nucleon's mass. Aside from understanding the origins of the various components of the nucleon's mass, these scalar matrix elements strongly affect the magnitude of certain dark matter (WIMP) - nucleon scattering cross sections. Their precise theoretical determination could thus offer input into the experimental detectability of dark matter/beyond the Standard Model (BSM) phenomena. On the lattice, sea quark nucleon sigma terms are represented by disconnected diagrams; in this work, we investigate the use of gradient flow (GF) in calculating the strange and charm nucleon sigma terms, and assess the degree to which GF can improve stochastic noise/systematics in our calculations. A problem particular to gradient flow of scalar matrix elements is the need to flow anti-quarks backwards in time; this can be recast as an "adjoint flow" problem that requires sophisticated hierarchical flow algorithms to achieve optimal speed and memory efficiency, the details of which will also be discussed. We present progress and preliminary calculations of strange and charm sigma terms using a mixed MDWF/HISQ action.

Speaker: Rohith Karur (The University of California, Berkeley)

17:10 Measuring Mass Splittings in Baryon SU(2) Multiplets

The inclusion of isospin-breaking corrections arising from electromagnetic interactions and the up–down quark mass difference has become timely in modern lattice QCD calculations, as the precision of many observables has reached the percent level. In this context, the RM123 method has played a pivotal role in recent years. In this work, we apply this framework to the study of baryon mass splittings. In particular, we present preliminary results for the mass splittings within the spin-1/2 and spin-3/2 baryon isomultiplets, obtained using twisted-mass ensembles tuned close to the isospin-symmetric point defined according to the Edinburgh/FLAG consensus.

Speaker: Christian Schneider (University of Cyprus)

16:10 → 17:30 Theoretical developments and applications beyond the SM

Convener: Shinichiro Akiyama (University of Tsukuba)

16:10 Searching for symmetric mass generation with staggered fermions in four dimensions

We conduct numerical simulations to map out the phase diagram and critical behavior of a lattice Higgs model composed of a massless staggered fermion transforming in the fundamental representation of $SU(2)$ and coupled to a scalar field in the adjoint representation of the group. The scalar action consists of quadratic, quartic terms and a derivative term. At fixed quartic coupling we explore a two dimensional parameter space finding a massless symmetric phase at weak coupling and a massive symmetric phase (SMG phase) at strong coupling. An intermediate anti-ferromagnetic phase separates these two regimes. These results are consistent with leading order weak and strong coupling expansions. However we find that the critical lines bounding the intermediate phase merge at a unique point where all fermion bilinear condensates vanish but fermion susceptibilities diverge as non-trivial powers of the lattice size. We conjecture that this point may correspond to the condensation of certain topological defects which are generated from a higher order term in a derivative expansion of the fermion determinant. The existence of this higher order term is unique to the symmetries of the model

Speaker: Gwen Hartshaw (Syracuse University)

16:30 Symmetric mass generation in a three-dimensional fermion lattice model

Symmetric mass generation denotes an unconventional continuum QFT mechanism, in which fermions acquire mass without a fermion bilinear condensate, i.e., without spontaneous symmetry breaking. The symmetric mass generation (SMG) mechanism can be studied in a Euclidean lattice model with two flavors of massless staggered fermions and two independent four-fermion interactions. In this talk, I will present the latest results for this model, reported in https://arxiv.org/abs/2512.24836 and https://arxiv.org/abs/2602.18360, obtained with the fermion bag Monte Carlo method on large three-dimensional lattices. We find evidence for conventional second-order critical points separating the massless fermion and broken phases, as well as the broken and SMG phases. The former transition is of the Gross-Neveu type, appearing, e. g., in twisted bilayer graphene, and the latter belongs to the 3D–XY universality class. Surprisingly, the two critical points appear to merge at a multicritical point with enhanced symmetry, which may explain the recently discovered second-order transition between the massless fermion and the SMG phase.

Speaker: Marina Krstic Marinkovic (ETH Zurich)

16:50 Anomalous Thermalization in the Presence of Generalized Symmetries on the Lattice

Non-integrable quantum many-body systems are generally expected to thermalize. That is, local observables relax to values predicted by a thermal ensemble constrained by the conserved quantities. However, in recent years, a growing number of exceptions have been identified, including many lattice Hamiltonians with gauge symmetry. In this talk, based on arXiv:2604.15820, I will outline how several of these exceptions can be explained by unresolved generalized symmetries. Once the corresponding conserved quantities, beyond conventional global charges, are taken into account, the dynamics can again be accurately predicted by a thermal ensemble. I will discuss partial isometries, which act as symmetry operators only on a subspace of the Hilbert space and provide a natural extension of conventional symmetries. In the studied lattice gauge theory Hamiltonians, partial isometries describe symmetries that exist only within specific superselection or winding sectors, thereby providing a framework for understanding novel anomalous out-of-equilibrium dynamics in quantum many-body systems.

Speaker: Thea Budde (ETH Zürich)

17:10 Hybrid Monte Carlo for the extended Kane-Mele-Hubbard model

The Hubbard model offers a powerful minimal description of molecules and materials, yet it neglects several effects and interactions observed in nature that give rise to a much richer variety of physics. For instance, extending the on-site interaction to include nonlocal interactions gives rise to a competition between strongly correlated phases, while incorporating spin-orbit coupling can lead to the emergence of exotic topological phases. With this in mind, we aim to develop a more realistic platform for simulating graphene and, potentially, other materials with similar lattice structures, such as transition metal dichalcogenides (TMDs). Specifically, we consider the extended Kane-Mele-Hubbard model, which features a Kane-Mele spin-orbit coupling term and nearest neighbor electron-electron interactions.

Simulating this model is particularly challenging when the nonlocal interactions become dominant over the on-site Hubbard interaction, where one encounters a severe sign problem at half-filling. For this reason, this regime has largely been avoided in the literature, and the Kane-Mele term likely compounds this difficulty further by introducing a complex phase at the level of the connectivity matrix. To investigate this regime, we develop a continuous auxiliary field formulation of the extended Kane-Mele-Hubbard model suitable for treatment with the Hybrid Monte Carlo (HMC) algorithm. Using this formalism, we characterize the severity of the sign problem across the model's parameter space, with the aim of establishing feasible regions of simulations, as a first step toward mapping out the model's full phase diagram.

Speaker: Finn Temmen (Forschungszentrum Jülich, IAS-4)

19:00 → 22:00 Banquet

Friday 31 July

09:00 → 10:30 Plenary session

Convener: Marina Krstic Marinkovic (ETH Zurich)

09:00 Tensor Network States and Lattice Gauge Theories

Tensor network states are powerpful variational guess states rooted in quantum information theory, which take into account the expected entanglement structure (area law) of physically relevant states and therefore significantly reduce the complexity of searching for them. I will give a brief introduction to these states and their special properties, and focus on their application for the study of Hamiltonian lattice gauge theories.

Speaker: Erez Zohar (Tel Aviv University)

09:30 Lattice Hamiltonian Formulations of Chiral Fermions and Chiral Gauge Theories

A nonperturbative definition of chiral gauge theories remains a long-standing open problem. Hamiltonian formulations, motivated in part by quantum simulation and tensor-network methods, offer a fresh perspective on old questions: fermion doubling and the fate of the Nielsen–Ninomiya theorem. Drawing on recent advances in our understanding of anomalies on the lattice, I will survey these developments and discuss the prospects and obstacles for gauging chiral symmetries in the Hamiltonian setting.

Speaker: Hersh Singh (Fermilab)

10:00 Lattice QCD: Helping set the stage for the future Electron-Ion Collider

The future Electron-Ion Collider (EIC) will be the next-generation facility focused on QCD research, bringing the age of quantitative QCD to maturity. Lattice QCD research will continue to play an important role in setting the stage for the EIC in the upcoming decade, as both the precision of lattice calculations keeps improving and the types of quantities and observables that can be calculated continues to expand. This talk will explore and reflect on the interplay between EIC physics and lattice QCD research.

Speaker: Prof. Christine Aidala

10:30 → 11:00 Coffee break

11:00 → 12:35 Plenary session

Convener: Prof. Martha Constantinou

11:00 Hadron structure from lattice QCD

Almost all the known mass of the universe can be attributed to nucleons. Accurate knowledge of the nucleon structure in terms of the quark and gluon degrees of freedom is essential for precisely extracting standard model parameters, including those in the neutrino sector. This knowledge is also crucial for our eventual discovery of physics beyond the standard model in colliders, fixed target experiments, and cosmic ray detectors. Over the past few years, a better understanding of the complementarity between first-principles lattice QCD calculations and experimental measurements (e.g. at the LHC and the future EIC) has emerged. In this talk, I will review recent results on hadron structure, with a particular focus on nucleon structure, and discuss future prospects.

Speaker: Gunnar Bali (Universität Regensburg)

11:45 Expert panel discussion

Scientific research and development in 2026: How can lattice field theorists adjust and thrive?

Speaker: Andreas Kronfeld (Fermi National Accelerator Lab. (US))

12:35 → 14:00 Lunch break

12:35 → 14:00 Networking and career development lunch

Organized by the LDIC

Convener: Christopher Monahan

14:00 → 15:40 Algorithms and artificial intelligence

Convener: Fernando Romero López (Uni Bern)

14:00 Agentic AI for QCD perturbation theory or: how I learned to stop worrying and love the bot

We recently completed a one-loop calculation of the RI/SMOM to $\overline{\text{MS}}$ renormalization scheme conversion factors for the $\Delta S = 1$ four-quark operators with four active quark flavors entirely by prompting an agentic AI system to generate Mathematica code. These are required perturbative inputs for lattice QCD simulations of weak processes such as the RBC/UKQCD calculation of $\Delta M_K$. We discuss our strategy and the methods we used to ensure correctness. We conclude with the prospects for using agentic AI to produce higher-loop results such as the matching factors needed to renormalize bi-local operators and higher-order Wilson coefficients.

Speaker: Erik Lundstrum (Columbia University)

14:20 AI-Assisted Higher-Order Hopping-Parameter Expansion in Lattice QCD

The hopping-parameter expansion (HPE) of the logarithm of the Wilson-fermion determinant expresses the coefficient of $\kappa^n$ as a sum over closed loops of length $n$. It is widely used in studies of heavy-quark QCD and in stochastic estimators of the fermion determinant. Although the expansion through sixth order, corresponding to LO and NLO, is well established, higher-order terms have rarely been constructed because the number of loop classes grows combinatorially. Through a collaboration between human researchers and AI coding agents, we have developed efficient algorithms for evaluating the N$^2$LO–N$^4$LO terms. Starting from a loop classification designed by the researchers, the AI agents proposed a trie-based algorithm that reuses partial matrix products shared by multiple loops, thereby reducing the computational cost of evaluating these higher-order contributions on a given gauge configuration. All results were verified to agree exactly with those obtained using a reliable but computationally expensive reference implementation. In this talk, we present the algorithms and discuss their potential applications.

Speaker: Tatsuya Wada (YITP/Kyoto University)

14:40 A variational framework for variance reduction in lattice field theory

The signal-to-noise problem limits the reach of many lattice calculations. We present a variational framework that recasts it as a transport problem: the loss of signal reflects a mismatch between the distribution one samples and the one needed to measure an observable, and can be reduced by transporting configurations to close that gap.
The optimal transport is typically determined either through a stochastic estimator based on Langevin dynamics or by parametrising it as a normalising flow trained with automatic differentiation. We discuss how the framework brings these methods under a common variational principle and present results for scalar theories.

Speaker: Pietro Butti (QTC, University of Southern Denmark)

15:00 Topology and thermodynamics from a machine-learned 4d SU(3) FP gauge action

Classically perfect fixed-point (FP) actions based on the renormalization group allow to reliably extract continuum physics from Monte Carlo simulations at coarse lattice spacings, thereby avoiding topological freezing. While these FP actions are very complicated, machine-learned gauge-equivariant neural networks enable accurate parametrizations and efficient simulations. In this talk I present our latest results from simulations of such a machine-learned FP action for 4-dimensional SU(3) gauge theory. In particular I discuss the continuum limits of some thermodynamical properties of the deconfinement phase transition, such as the latent heat and the interface tension, and the topological susceptibility based on a machine-learned FP topological charge operator.

Speaker: Urs Wenger (University of Bern)

15:20 Lattice QCD on the 16-cell honeycomb

The 4-dimensional hypercubic lattice has a symmetry group with 384 elements. The 16-cell honeycomb lattice has 3 times as many elements, hence a larger symmetry. Motivated by this fact we discretize lattice QCD on this lattice and observe better scaling for gauge observables and better chiral properties for the Wilson-type Dirac operator. Even though a lattice site has 24 neighbors and not 8 as with the hypercubic lattice, the over-all cost gain in dynamical simulations is expected to be significant due to the better scaling properties.

Speaker: Daniel Nogradi

14:00 → 15:40 Hadronic and nuclear spectrum and interactions: I

Convener: Michael Wagman

14:00 Hyperon forces from lattice QCD at the physical point

A first-principles determination of hadron interactions is one of the most important subjects in particle, nuclear, and astrophysics. In particular, the determination of hyperon forces plays a crucial role in understanding not only the structure of hypernuclei but also the equation of state of dense matter and the internal structure of neutron stars.
In this talk, we will present lattice QCD studies of hyperon forces, including the Lambda-Lambda, N-Xi, and N-Omega interactions. Employing the HAL-conf-2023 gauge configurations generated by the HAL QCD Collaboration in (2+1)-flavor QCD at the physical point, m_pi = 137 MeV, we calculate four-point correlation functions using the supercomputer Fugaku and extract the interaction potentials and scattering parameters by the HAL QCD method. The fate of exotic dibaryons will be discussed, and comparisons with experiments will also be presented.

Speaker: Takumi Doi

14:20 Nucleon-Nucleon and S = -1 Nucleon-Hyperon Interactions

In this talk, I will present preliminary results for nucleon-nucleon and nucleon-hyperon scattering on behalf of the BaSc collaboration. For both systems, I will discuss the ensembles used and the extracted spectra; collaborators will focus on the nucleon-nucleon finite-volume scattering analysis in separate talks. For the $S = -1$ nucleon-hyperon portion, I will showcase the current state of our analysis, demonstrate the importance of partial-wave mixing, and present the extraction of multiple partial-wave phase shifts

Speaker: Malcolm Lazarow (UC Berkeley)

14:40 Baryon-baryon interactions in the $S = -1$ channel and inelastic contaminations in physical-point lattice QCD

We report the current status of first-principles lattice QCD results for the strangeness $S = -1$ sector of baryon-baryon interactions with the physical masses. We measure the two- and four-point functions on the (2+1)-flavor gauge configurations (HAL-conf-2023) [1] generated on the physical point, $(m_\pi, m_K) = (137, 502)~\mathrm{MeV}$. We calculate the Euclidean-time dependence of the potentials by the HAL QCD method [2] for the coupled channel, $N\Lambda$-$N\Sigma$ ($I = 1/2$), and the single channel, $N\Sigma$ ($I = 3/2$). To reduce the inelastic-state contaminations, we further perform the extrapolation to $t \to \infty$ assuming an exponential time dependence of the contaminations. We demonstrate the stability and robustness of the extrapolation, and compare the results with the phase shifts from scattering experiments and femtoscopic correlations from high-energy nuclear collision experiments.

References

• [1] "Scale setting and hadronic properties in the light quark sector with (2+1)-flavor Wilson fermions at the physical point", T. Aoyama, T. M. Doi, T. Doi, E. Itou, Y. Lyu, K. Murakami, T. Sugiura, Phys. Rev. D 110 (2024) 9, 094502.
• [2] N. Ishii, S. Aoki, T. Hatsuda et al. [HAL QCD collaboration], Phys. Rev. Lett. 99 (2007) 022001; Phys. Lett. B 712 (2012) 437; PTEP 2012 (2012) 01A105; Front. in Phys. 8 (2020) 307.

Speaker: Koichi Murase (The University of Osaka)

15:00 Baryon-Baryon Scattering at the SU(3) Flavor-Symmetric Point from Lattice QCD

We present a high-statistics study of nucleon-nucleon scattering in the SU(3) flavor-symmetric limit of QCD, where the light and strange quark masses are tuned to a common value corresponding to $m_\pi \approx 714$. We perform an extraction of NN scattering phase shifts across multiple partial waves using the Lüscher finite-volume quantization condition with multiple boost frames. The high-statistics finite-volume spectra allow us to constrain the effective range expansion parameters and characterize the energy dependence of the scattering amplitudes. We discuss the implications of these results for the structure of baryon-baryon interactions in the SU(3) limit.

Speaker: Joseph Moscoso (UMD CP)

15:20 Lattice QCD study on $S=+1$ kaon-nucleon interactions and the $\Theta^+$ pentaquark at the physical point: updated analysis

Kaon-nucleon (KN) interactions with the strangeness $S=+1$ provide a testing ground for comparing lattice QCD with experiments. They also play an important role in understanding the partial restoration of chiral symmetry and in clarifying whether genuine pentaquarks exist. In this study, the S-wave KN interactions are derived using the HAL QCD method with $N_f=2+1$ quark flavors at the physical point, $m_\pi \approx 137$ MeV. We use the configurations generated by the HAL QCD Collaboration, “HAL-conf-2023”. In this talk, we present an updated analysis of the KN interactions, revisiting the results of our previous study [1].
The resulting interaction potential exhibits a purely repulsive behavior for isospin $I=1$, while for $I=0$ a small attractive pocket is observed in addition to repulsion. The obtained phase shifts for $I=1$ agree with experiments at small momenta. In addition, our results indicate that there are no bound or resonant states corresponding to the $\Theta^+$ pentaquark in the S-wave system. Furthermore, we extract the higher-partial-wave phase shifts, ignoring the dependence of the potentials on both spin and angular momentum; the resulting phase shifts deviate significantly from experiment and partial-wave analysis, particularly in the $I=0$, P-wave channel, suggesting a strong attractive contribution from this dependence.

[1] K. Murakami et al. [HAL QCD], Phys. Rev. D 113, no.5, 054506 (2026).

Speaker: Kotaro Murakami

14:00 → 15:40 Hadronic and nuclear spectrum and interactions: II

Convener: Andrew Jackura (William & Mary)

14:00 T_{cc} from coupled DD* - D*D* scattering incorporating left-hand cuts and local operators

In this talk I will present preliminary results from an ongoing study of coupled $DD^* - D^*D^*$ scattering on the lattice. To obtain the finite-volume spectrum of the system we incorporate a variety of scattering interpolators in both channels, in addition to a local diquark-antidiquark operator, whose role in determining the energies of excited states for this system has recently emerged. The spectrum is obtained using two ensembles, generated by the CLQCD collaboration, with a pion mass $m_\pi \approx 305$ MeV at two volumes: $L = 32, 48$. In the subsequent scattering analysis we employ the two-body adapted Finite-Volume Unitarity (FVU) quantization condition to constrain infinite-volume interactions in the system. The left-hand branch cuts in direct- and cross-channel scattering amplitudes, induced by the one-pion exchange, are explicitly addressed in the quantization condition. Finally, preliminary fits to the lattice spectra, using a variety of parametrizations of low-energy contact interactions, are shown.

Speaker: Ivan Vujmilovic

14:20 Precise calculation of the low-lying charmed baryon spectrum on CLS ensembles

We determine the spectra of singly- and doubly-charmed baryons on $N_f=2+1$ ensembles generated by the Coordinated Lattice Simulations (CLS) effort with non-perturbatively improved Wilson fermions. The baryon masses are calculated along three trajectories in the plane spanned by the light and strange quark masses, two of which intersect close to the physical point, and a third approaching the SU(3) chiral limit. The pion mass varies from $420\,$MeV down to $130\,$MeV. The continuum limit is taken using several lattice spacings ranging from $a \approx 0.10\,$fm to $0.04\,$fm, while spatial volumes are kept large enough to suppress finite-size effects. The ground state masses in the spin-$1/2$ and spin-$3/2$ channels are extracted and compared with experimental measurements and previous lattice determinations.

Speaker: Archana Radhakrishnan

14:40 Determination of the Roper resonance with two- and three-body unitarity

The Roper resonance does not fit many quark model predictions or lattice QCD calculations. One reason could be the strong three-body dynamics for this channel. The analysis of the Roper with lattice QCD requires a hadronic coupled-channel amplitude in the two- and three-body channels.
As a first step, we develop an amplitude that consistently and unitarily includes the $\pi N$ and $\pi\pi N$ channels, which will allow us to map finite-volume energies from lattice QCD to the infinite-volume amplitude using the finite-volume unitarity (FVU) approach. Available partial-wave data in the Roper and the isobar sub-channels are described, allowing for the most precise pole determination of the Roper resonance to date.

Speaker: Jinzi Wu (The George Washington University)

15:00 Investigating the role of tetraquark operators in lattice QCD studies of the $a_0(980)$ and $κ$ resonances

We report on our completed study of the role of tetraquark interpolating operators in the isodoublet strange $\kappa$ and isovector nonstrange $a_0(980)$ scalar channels using $N_f = 2+1$ lattice QCD at $m_\pi \simeq 230\:\mathrm{MeV}$. We compare finite-volume spectra extracted using Hermitian correlation matrices constructed with and without tetraquark operators and find substantial differences in the resolved energy levels. The spectra are then used in the $2\to2$ finite-volume quantization condition to constrain the scattering $K$-matrix, allowing for a qualitative comparison of the resulting descriptions. Time permitting, we also present a progress report on our study of higher partial waves in the di-nucleon system at a heavy, flavor-symmetric point, $m_\pi = m_K \simeq 714\:\mathrm{MeV}$.

Speaker: John Meneghini (Carnegie Mellon University)

15:20 Low-Energy $\bar{D}N$ Scattering from Physical-Point Lattice QCD

The $\bar D N$ system is one of the simplest hadronic systems containing an open-charmed meson and a nucleon, yet its low-energy interaction remains to be fully understood. Existing phenomenological models predict interactions ranging from sufficiently strong attraction to form a pentaquark state to weak attraction or repulsion. On the experimental side, higher-statistics LHC Run 3 data are expected to provide improved constraints, making first-principles lattice QCD calculations increasingly relevant for comparison with forthcoming experimental measurements and phenomenological models.
In this talk, we present updated results for the $\bar D N$ potential and its $s$-wave scattering parameters obtained using the HAL QCD method. (2+1)-flavor lattice QCD simulations were performed at the physical point with gauge configurations generated by the HAL QCD Collaboration (“HAL-conf-2023”) on a $96^3 \times 96$ lattice with pion mass $m_\pi \simeq 137$ MeV and lattice spacing $a \simeq 0.0844$ fm. The present work includes additional studies of systematic uncertainties together with a comparison with effective model predictions. We observe an attractive phase shift in the low-energy region of the $I=0$ channel and a repulsive phase shift in the $I=1$ channel. No evidence for a pentaquark bound state is found in either channel.

Speaker: Wren Yamada (RIKEN)

14:00 → 15:40 QCD at nonzero temperature and density

Convener: Ivan Horvath

14:00 Bottomonium and B mesons at non-zero temperature on anisotropic lattices

We study bottomonium and B mesons at non-zero temperature, using lattice NRQCD for bottom quarks and an ${\cal O} (a)$ improved Wilson action for $N_f = 2+1$ flavors of light quarks on anisotropic lattices. We consider two sets of FASTSUM ensembles, with an anisotropy of $\xi = 3.45$ for the B meson study and $\xi = 7.02$ for the bottomonium study. The pion mass is approximately the same, $m_\pi \sim 380$ MeV. Temperature is varied by changing the number of lattice sites along the time direction, allowing us to examine the spectral properties of these channels in detail. Here, we report on the current status of our studies.

Speaker: Prof. Seyong Kim (Sejong University)

14:20 Diffusion of heavy quarkonia on the lattice

The interaction of heavy quarkonium in QGP within the potential non-relativistic QCD framework can be characterized in terms of transport coefficients related to the correlators of color electric fields connected by adjoint Wilson lines. We present a lattice calculation of these correlators with both gradient flow and multilevel algorithms and extract the relevant transport coefficients. We will also compare the correlator with the closely related one used for the study of heavy quark diffusion.

Speaker: Viljami Leino (U. Southern Denmark, QTC)

14:40 Quarkonium properties at non-zero temperature from lattice QCD

We study charmonium and bottomonium properties at nonzero temperature using lattice QCD covering temperatures in the range 153 MeV $<T<$ 305 MeV. We compute Euclidean correlation functions using both point meson operators, where the quark and antiquark fields are located at the same spatial point, and extended meson operators, where the quark and antiquark fields are spatially separated to enhance overlap with physical quarkonium states.

We show for the first time that the masses and widths obtained from point and extended meson operators are consistent with each other, providing an important cross-check for the spectral analysis. We find that the in-medium quarkonium masses show no significant temperature dependence within uncertainties, in contrast to common expectations based on color screening. On the other hand, the thermal widths clearly increase with temperature, indicating substantial in-medium broadening of quarkonium states.

Speaker: Jorge Luis Dasilva Golan (brookhaven National Laboratory)

15:00 Non-static mesonic screening masses up to electroweak-scale temperatures

We report on the exploration of thermal QCD with $N_f=3$ flavours of $O(a)$-improved massless Wilson fermions up to electroweak-scale temperatures. We present results on screening masses at 12 temperatures ranging from 1 GeV to 165 GeV, in several flavor non-singlet mesonic channels, including the first and second non-static Matsubara sectors with frequencies 2πT and 4πT, respectively. For each temperature we have simulated 3 or 4 values of the lattice spacing, so as to perform the continuum limit extrapolation with confidence.
The implementation of random sources significantly enhances the signal-to-noise ratio for non-static correlators, while simultaneously improving the precision of previously determined static screening masses by up to an order of magnitude.
Our continuum-extrapolated results provide a comprehensive picture of the QCD screening spectrum across a wide temperature range. A comparison with next-to-leading order perturbative predictions reveals that non-perturbative contributions remain highly relevant even at the highest temperatures explored.

Speaker: Pietro Rescigno (RIKEN R-CCS, Kobe)

15:20 Finite-Temperature Effects on Gluon Screening Masses in Dense Two-Color QCD

We investigate the chemical-potential ($\mu$) dependence of gluon screening masses in two-color QCD ($\mathrm{QC_2D}$) at finite density using lattice simulations.

Previous studies on this topic have reported conflicting results. One group concluded that both the electric and magnetic screening masses are independent of $\mu$, whereas another reported that the electric screening mass increases with $\mu$.

To resolve this discrepancy, we calculate the gluon propagator in the Landau gauge and extract the screening masses at various chemical potentials and at several temperatures, $T \simeq 40, 106,$ and $127~\mathrm{MeV}$.

Our results show that the magnetic screening mass remains independent of $\mu$ at all temperatures. In contrast, the electric screening mass exhibits a clear temperature dependence: it is independent of $\mu$ at low temperature, $T \simeq 40~\mathrm{MeV}$, while it increases with $\mu$ at higher temperatures, $T \simeq 106$ and $127~\mathrm{MeV}$.

This high-temperature behavior is qualitatively consistent with the $\mu$ dependence predicted by effective models. These findings suggest that the discrepancy between the two previous studies arises from finite-temperature effects.

Speaker: Kei Tohme (Kyoto University)

14:00 → 15:40 Quantum computing and quantum information

Convener: Natalie Klco (Duke University)

14:00 Trapped-ion quantum simulation of (1+1)D SU(2) lattice gauge theory via loop-string-hadron formulation

We present a quantum simulation of the SU(2) lattice gauge theory in 1+1 dimensions with one flavor of fermions, performed using both Quantinuum's trapped-ion H2-2 hardware and its emulator. This work is based on the loop-string-hadron (LSH) formulation of the gauge theory, and is distinguished by keeping the local bosonic degrees of freedom rather than integrating them out. Furthermore, we access physics that is above the typical $j=1/2$ truncation that is commonly applied for SU(2) quantum simulations. We include an electric-field degree of freedom that is digitized using a true multiqubit ``register'' for representing the bosonic quantum number. Our simulation therefore showcases several features that would characterize a large-scale quantum simulation in more than 1+1 dimensions, while relying solely on optimizations that should scale polynomially with the lattice size.

Speaker: Jesse Stryker (Lawrence Berkeley National Laboratory)

14:20 Arbitrary-Distance Quantum Error Correction with Gauss's Law for Lattice Gauge Theories

We introduce a general framework for taking advantage of gauge symmetry to build quantum error-correcting codes (QECCs) that can be applied to Hamiltonian simulations for lattice gauge theories (LGTs) on quantum hardware. Our framework has the following features: (i) reduction of the overhead needed in physical qubits compared to alternative methods; (ii) arbitrary code distance, and therefore arbitrarily high robustness against realistic noise models; (iii) compatibility with widely studied QECCs, by using Gauss's law constraints to decode error patterns with increased accuracy; (iv) applicability to non-Abelian LGTs. We provide examples of explicit code constructions within our framework to illustrate these points, and discuss the path forward to fault-tolerant quantum simulations of LGTs on hardware.

Speaker: Neel Modi (UC Berkeley, Lawrence Berkeley National Lab)

14:40 Tightening energy-based boson truncation bound using Monte Carlo-assisted methods

Quantum simulation offers a promising framework for quantum field theory calculations. Obtaining reliable results, however, requires careful characterization of systematic uncertainties. One important source is the boson truncation error, which arises from representing infinite-dimensional local Hilbert spaces with finite-dimensional ones. Previous studies have examined this problem from several perspectives. In particular, Jordan, Lee, and Preskill (arXiv:1111.3633) derived an energy-based bound applicable to generic low-energy states across a broad class of field theories. However, this approach often yields overly conservative bounds, especially at large volumes. In this talk, we present a new methodology that significantly tightens the energy-based boson truncation bound through two complementary advances: an improved analytic derivation and a Monte Carlo-based numerical procedure. We demonstrate the method in (1+1)-dimensional scalar field theory and (2+1)-dimensional U(1) gauge theory in the dual formalism. Our approach substantially mitigates the volume dependence of the required truncation cutoff, achieving reductions nearly proportional to the volume in some cases and to the square root of the volume in others.

Speaker: Jinghong Yang

15:00 Reducing circuit depth for $SU(3)$ lattice gauge theory with permutation-symmetric $SU(N)$ Clebsch-Gordan coefficients

Quantum simulations of $SU(N)$ lattice gauge theory (LGT) in the irrep basis require classical precomputation of Clebsch-Gordan coefficients (CGCs). Strategically choosing the direct-sum basis to maximize the symmetries of the CGCs plausibly translates into gate count reductions for the time-evolution circuit. One such choice occurs when two or more $SU(N)$ irreps in a tensor product are identical. Then, it is possible to choose a direct-sum basis which further 'diagonalizes' the $S_{n}$ permutation symmetry of the tensor product such that the identical $SU(N)$ irreps also transform as a representation of $S_{n}$. We achieve $S_{n}$ diagonalization by augmenting a standard numerical algorithm for $SU(N)$ CGC computation with an additional step which applies a set of Hermitian Young projection operators onto the highest-weight state of each $SU(N)$ irrep; by splitting the highest-weight state into subspaces corresponding to irreps of $S_{n}$, all CGCs computed from this data will also transform as $S_n$ irreps. Empirically, using 'symmetrized' CGCs to compute matrix elements of the $SU(3)$ Kogut-Susskind (KS) Hamiltonian reduces the number of nonzero matrix elements by more than 50% relative to 'unsymmetrized' CGCs for irrep trunctions with nontrivial Hilbert space multiplicities. Since the depth of the Trotterized time-evolution circuit for $SU(3)$ LGT scales linearly with the number of nonzero KS Hamiltonian matrix elements, using symmetrized CGCs directly yields the same reduction in circuit depth.

Speaker: Jason Elhaderi (University of Illinois, Urbana-Champaign)

15:20 Large-$N$ Phase Structure of $q$-Deformed Yang--Mills Theory in 2+1 Dimensions

We study a $q$-deformed ${\rm SU}(N)$ Yang-Mills theory in 2+1 dimensions using the lattice Hamiltonian formalism. The deformation introduces a finite level $k$, which truncates representations and allows the theory to interpolate between a confining regime and a topologically ordered regime. Treating $N$, the Yang-Mills coupling $g$, and $k$ as independent control parameters, we analyze the resulting phase diagram in the large-$N$ limit. In particular, we focus on the scaling behavior governed by the 't Hooft coupling and the ratio $k/N$. A variational mean-field analysis shows that the topologically ordered phase can survive at large $N$ when the cutoff level is scaled appropriately with $N$. This result suggests that quantum-group truncations of non-Abelian gauge theories possess a richer continuum and large-$N$ structure than might be expected from observations at $N = 2$ and $3$. Extending the mean-field perspective beyond the present analysis would further clarify the interplay between confinement and topological order and provide useful benchmarks for future quantum-computational studies of gauge theories.

Speaker: Hiromasa Watanabe (Keio University)

14:00 → 15:40 Structure of hadrons and nuclei

Convener: Fangcheng He

14:00 Instantons from Lattice QCD using Gradient Flow in Pion Form Factors

The instanton liquid model is believed to capture the main features of vacuum QCD dynamics. Recently, multiple predictions for hadron structure functions have been derived and compared with experimental measurements and lattice QCD calculations, showing general agreement. In order to explore the precision of the instanton liquid model, one has to compare its predictions with non-perturbative simulations in a regime dominated by instanton dynamics.

This has been performed for two gluon-sensitive observables: the gluon Green’s function and the strong running coupling constant [1]. In this contribution, we propose to study a fermionic observable, the pion vector form factor, for which instanton liquid model predictions have been discussed in [2]. We use the Wilson flow to single out the dominant instanton contribution from lattice QCD gauge-field configurations. We describe the details of our numerical setup and present first preliminary results.

Interestingly, we find that at positive Wilson flow time the statistical signal for hadronic matrix elements, particularly at higher momentum transfer, is significantly improved. This suggests that Wilson flow may provide a useful way to access fermionic observables in a regime where instanton-dominated dynamics can be more clearly isolated.

Reference
[1] Athenodorou, Ph. Boucaud, F. De Soto, J. Rodríguez-Quintero, and S. Zafeiropoulos.Gluon Green functions free of Quantum fluctuations. Phys. Lett. B, 760:354–358, 2016.
[2] Wei-Yang Liu, Edward Shuryak, and Ismail Zahed, Phys. Rev. D 109, 074029 (2024). doi:10.1103/PhysRevD.109.074029

Speaker: Vaibhav Chahar (Jagiellonian University, Poland)

14:20 Toward a continuum limit determination of light meson charge radii with large-volume, physical point $N_f=2+1$ lattice QCD

We report a preliminary study of light meson charge radii based on the PACS10 configurations generated by the PACS Collaboration at the physical point in spatial volumes larger than $(10\,\text{fm})^3$. Lattice QCD calculations of charge radii are generally subject to several sources of systematic uncertainty, including chiral extrapolation, discretization effects, finite-volume effects, and the parametrization of the momentum transfer dependence of the form factor. The PACS10 configurations enable us to address the first three sources of uncertainty within a unified framework. In addition, we employ a model-independent extraction method to eliminate the systematic dependence on a particular fit ansatz. Our preliminary estimates of the charge radii of the $\pi^+$, $K^+$, and $K^0$ are in agreement with experimental measurements and previous lattice-QCD determinations, while achieving reduced uncertainties.

Speaker: Kohei Sato (Center for Computational Sciences, University of Tsukuba)

Lattice2026.pdf

14:40 Electric and magnetic polarizability of pions from four-point functions on nHYP ensembles

The electric and magnetic polarizability of hadrons encodes information on their internal structure. Traditionally, the background field method has been used to calculate polarizabilities. However, recent work has demonstrated the effectiveness of using four-point functions for computing polarizabilities of charged and neutral hadrons. Our previous work employed a quenched Wilson action on a lattice with pion masses ranging from 1100 MeV to 370 MeV. In this work, we have employed a number of improvements, including a dynamical action (nHYP), smaller pion masses (220 MeV and 315 MeV), and a number of lattice volumes.

Speaker: sudip shiwakoti (Baylor University)

15:00 LMA performance on twisted-mass fermions ensembles at physical pion masses

In this talk, we present a study of the performance of low-mode averaging (LMA) techniques on twisted-mass fermion ensembles at near-physical quark masses, assessing both their theoretical foundations and practical cost-effectiveness in contemporary lattice QCD. We focus on light-quark meson and baryon observables and perform a detailed numerical investigation of the resulting variance reduction. For mesonic observables, we compare two implementations of LMA: a standard exact approach based on explicitly computed low-lying eigenmodes and an approximate high-statistics variant that exploits multigrid techniques. In addition, we present a comprehensive study of the eigenvalue density of the massless Wilson operator and related spectral observables, providing further insight into the role of low modes in lattice calculations.

Speaker: Dr Antonio Evangelista (University of Cyprus)

15:20 Nonperturbative Hadronic Structure of the Photon

Photons can acquire a hadronic structure through quantum fluctuations, effectively becoming a superposition of the $U(1)$ gauge boson of QED and QCD quark-gluon configurations. Consequently, in electron-proton scattering, partons from both the resolved photon and proton can participate in strong interactions, revealing the resolved photon's hadronic structure. Although this nonperturbative structure remains poorly understood, it is critical for photoproduction of jets studies at the EIC, where the process is particularly sensitive to the gluon distribution of the proton. Additionally, QCD factorization is seen to be violated by a factor of $\sim 0.34$ when resolved photons contribute to the photoproduction of dijets alongside pointlike photons at HERA, raising a critical question of whether factorization is genuinely broken for resolved photons or whether the issue stems from the lack of precise knowledge of the resolved photon's hadronic structure. As a unique opportunity to unravel the largely uncharted hadronic structure of the photon, we present ongoing progress in the first lattice QCD program to compute the photon's $x$-dependent hadronic structure using the RBC/UKQCD domain wall fermion ensembles with lattice spacings of $0.06,~0.09$ and $0.12$ fm.

Speaker: Raza Sufian (New Mexico State University / BNL)

14:00 → 15:40 Theoretical developments and applications beyond the SM

Convener: Robert Mawhinney (Columbia University)

14:00 Qubit-Regularized Gauge Theories on Plaquette Chains

Traditional Hamiltonian lattice gauge theory (LGT) regularizes continuum gauge fields using bosonic link degrees of freedom, leading to infinite-dimensional local Hilbert spaces. Qubit regularization takes a different route: it builds new gauge-invariant quantum lattice systems with finite-dimensional local Hilbert spaces from the outset and obtains continuum relativistic quantum field theories (QFTs) by tuning to quantum critical points. In our work, we do not view these systems as finite-dimensional truncations of an existing LGT. Instead, we regard them as a new class of gauge-invariant lattice gauge theories in their own right and ask whether they possess continuum limits and whether some of the continuum QFTs that emerge in these limits correspond to conventional continuum gauge theories.

As a first application of this research direction, in this talk I will discuss simple qubit-regularized SU(2) and SU(3) LGTs on plaquette chains. Both models give rise to nontrivial, asymptotically safe continuum relativistic QFTs. The SU(2) model maps to the transverse-field Ising model in a longitudinal field, with a continuum limit described by the 2D Ising conformal field theory (CFT) in the ultraviolet (UV) and massive relativistic excitations in the infrared (IR) governed by Zamolodchikov’s $E_8$ QFT. The SU(3) model is equivalent to the three-state quantum clock model in a magnetic field, whose continuum limit is governed by the 2D $\mathbb{Z}_3$ parafermion CFT in the UV and a massive relativistic three-state Potts field theory in the IR. Our lattice models allow us to interpret these traditional continuum QFTs as gauge theories. We have computed universal ratios involving string tensions and the lowest glueball masses, which are standard physical observables in conventional gauge theories. This research points a way toward explorations in higher dimensions.

Speaker: Rui Xian Siew (Duke University)

14:20 Studying QED3 in radial quantization: coarse lattice study

We report on a study of fully interacting QED3 in radial quantization with overlap fermions. By including a soft breaking mass for the flavor symmetry, and by varying the refinement level of the base icosahedral lattice as L=1, 2, 4, the possible spontaneous symmetry breaking (SSB) is studied. By using the radial quantization, the scaling symmetry is preserved, which makes it an ideal setup to study near-conformal theory; in fact, with a large enough number of flavors, QED3 is known to be conformal, where its breaking would be triggered by a mechanism similar to the chiral symmetry breaking in 4D QCD. We discuss the (non-)existence of the condensate, which is the order parameter of the SSB, and the current-current correlators, for which the continuum formula is known in CFT.

Speaker: Nobuyuki Matsumoto (Boston University)

14:40 Euclidean correlation functions in quantum gravity

We discuss the calculation of Euclidean correlation functions in lattice quantum gravity and in the low energy effective theory using perturbation theory. In the low energy theory the leading contributions are universal predictions of quantum gravity, depending only on Newton's constant, thus providing an important test for lattice calculations. We present the calculations in the low energy theory and give a first look at comparisons to numerical lattice results.

Speaker: John Laiho (Syracuse University)

15:00 One-loop perturbation theory estimates for exponential clover-improved Wilson fermions

In recent years, a lot of evidence has been gathered for exponential clover Wilson fermions suggesting that cutoff effects are reduced compared to standard clover improved Wilson fermions. The exponential clover implementation gives rise to new vertices in perturbation theory, which need to be incorporated in perturbative calculations of, e.g., improvement coefficients. Here, we study possible contributions to the critical mass and $c_\mathrm{A}$, the improvement coefficient of the non-singlet axial-vector current, to one-loop order. For our calculations, we exploit the Schrödinger functional finite-volume renormalisation scheme at vanishing quark mass, with subsequent continuum extrapolations to estimate associated cutoff effects. Our numerical calculations with both plaquette and tree-level Symanzik-improved gauge action show that the critical mass receives additional contributions at one-loop order, while $c_\mathrm{A}$ is free of such contributions.

Speaker: Juan Falceto

15:20 Non-perturbative renormalization of the energy-momentum tensor in $N_f=3$ Wilson lattice QCD

We present a non-perturbative determination of the renormalization constants of the non-singlet components of the QCD energy-momentum tensor on the lattice. The calculation is carried out with the Wilson plaquette gauge action and $N_f=3$ flavours of $O(a)$-improved Wilson fermions. The four independent renormalization constants, associated to the sextet and the triplet representations of the hypercubic group, are fixed by imposing lattice versions of continuum Ward identities in the presence of shifted and twisted boundary conditions. The resulting renormalization conditions involve only one-point functions of the energy-momentum tensor and can be implemented with high numerical precision. The renormalization constants are computed with percent-level accuracy for bare couplings in the range $0\leq g_0^2\leq 0.96$.

Speaker: Matteo Bresciani (Trinity College Dublin)

15:40 → 16:10 Coffee break

16:10 → 17:30 Algorithms and artificial intelligence

Convener: Xiao-Yong Jin

16:10 Tensor renormalization group for four-dimensional SU(N) gauge theories

We apply the tensor renormalization group method to SU(N) non-Abelian gauge theories in three- and four-dimensional spacetime. Using a sampling approach for the gauge group elements, we obtain expectation values that are consistent with perturbation theory in both the strong- and weak-coupling regions. We propose several distributions for the random sampling and compare their performance at different couplings. We focus mainly on the SU(2) theory and discuss the extension of the method to the SU(3) case.

Speaker: Katsumasa Nakayama (RIKEN)

16:30 Tensor renormalization group analysis of correlators in Yang-Mills theory

The tensor renormalization group (TRG) is a numerical method that is, in principle, free from the sign problem and is regarded as a promising candidate for first-principles calculations of finite-density QCD. While many successful studies have been carried out for scalar and fermionic field theories, its application to gauge theories remains under development. In this talk, we propose a method for computing correlators of Wilson loops based on the impurity approach, which is applicable to arbitrary gauge groups in arbitrary dimensions. The method can also be extended to cases with complex coupling constants. As a concrete example, we compute correlators of plaquettes in three-dimensional pure Yang–Mills theory using this approach and compare the results with those obtained from Monte Carlo simulations.

Speaker: Takaaki Kuwahara (The University of Tokyo)

16:50 Simulating the string formulation of SU(3) lattice gauge theory

We review the string formulation of gauge fields on a finite lattice with periodic boundary conditions, as proposed by Batrouni and Halpern in 1984. Simulation results using the Hybrid Monte Carlo algorithm are reported. The properties of the molecular dynamics force under gauge transformations are compared with the Wilson formulation and we discuss the application to Fourier acceleration.

Speaker: Benjamin Izett (ETH Zürich)

17:10 Comparison of Smearing Kernels for Field-Transformation HMC via the Master-Field Technique

The Field-Transformation Hybrid Monte-Carlo (FTHMC) algorithm potentially mitigates critical slowing down by combining the HMC with an invertible field transformation, originally proposed by Lüscher and motivated as trivializing the theory. In our previous study, using a single Jacobian-computable smearing step resembling stout smearing in 2+1 domain-wall fermion simulations, we found a reduction of exponential autocorrelation times of Wilson-flowed infrared observables that grows with the smearing parameter. Here we extend this study to the choice of the transformation kernel itself: plaquette- and rectangle-based smearing steps and their two-step compositions, applied at fixed smearing parameter to quenched ensembles on 24³×40 lattices, together with HMC baselines and a scan of the trajectory length. Autocorrelation times of Wilson-flowed energy densities are again computed with the master-field technique, enabling a comparison from a moderate number of configurations at matched molecular-dynamics cost. We identify which kernel combinations decorrelate infrared observables most efficiently and discuss the dependence on flow time and trajectory length.

Speaker: Shuhei Yamamoto (BNL)

16:10 → 17:50 Hadronic and nuclear spectrum and interactions

Convener: Joseph Moscoso (UMD CP)

16:10 Spectral bounds and the design of interpolating operators

Spectroscopy in lattice field theory begins with the choice of interpolating operators used to couple to the desired quantum numbers. Since the Hilbert spaces of bosonic theories such as lattice QCD are essentially infinite dimensional, standard spectroscopy techniques depend strongly on this choice in practice and require implicit assumptions about unphysical operator-state overlaps. More robust analysis techniques that require milder assumptions but nevertheless produce two-sided spectral bounds are discussed and shown to be of practical use in analysis of two-nucleon systems.

Speaker: William Detmold

16:30 Discretization effects in baryon-baryon scattering

Multi-hadron spectroscopy is complicated by discretization and excited-state effects that must be disentangled to reliably resolve finite-volume energy differences entering quantization conditions. I will present precise constraints on baryon-baryon scattering from block Lanczos analyses of large interpolator sets, for which two-sided bounds provide constraints on the locations of LQCD energies whose validity does not require excited-state effects to be small. Results from 11 gauge-field ensembles spanning a factor of two in lattice spacing and factor of twenty-seven in physical volume with fixed (albeit unphysical) mpi/MN = 0.5 enable detailed studies of discretization effects, finite-volume effects, and quark-mass-mistuning effects. Discretization effects can be clearly resolved, even within the relatively loose constraints provided by two-sided gap/variational bounds, and significant preferences are found for one class of models of discretization effects under the same mild assumptions on spectral gaps.

Speaker: Michael Wagman

16:50 Finite-volume analysis of the H-dibaryon including left-hand-cut effects

In this talk, I'll show our first implementation of the finite-volume $N/D$ representation to study two-baryon interactions from lattice QCD data. We include the left-hand cut induced by one-pion exchange in this formalism, and study the H-dibaryon at the SU(3)$_\text{F}$-symmetric point, with a pion mass around $417$MeV. The $N/D$ formalism is also compared to the Luscher quantization condition, used to describe the same system via effective-range expansions. Our results show a mild but statistically significant effect produced by the inclusion of the left-hand cut, especially on the binding energy of the shallow bound H-dibaryon here.

Speaker: Lin Qiu (Old Dominion University)

17:10 The H-dibaryon at $m_\pi \simeq 200~\mathrm{MeV}$ from lattice QCD

We present a preliminary lattice QCD study of the H-dibaryon at a close-to-physical pion mass from a spectroscopic analysis of the strangeness $S=-2$, iso-singlet baryon-baryon system on the CLS D200 ensemble. This ensemble has $m_\pi \simeq 200~\mathrm{MeV}$ and $m_K \simeq 480~\mathrm{MeV}$, using a $64^3 \times 128$ lattice with spacing $a \simeq 0.065~\mathrm{fm}$ and open temporal boundary conditions. We determine the finite-volume spectrum from a GEVP analysis using a basis of $\Lambda\Lambda$, $N\Xi$, and $\Sigma\Sigma$ interpolating operators with multiple momentum combinations. We then perform a coupled-channel finite-volume analysis using different $K^{-1}$-matrix parametrizations over a broad energy range, featuring energy dependence and channel coupling. We discuss the implications of our preliminary results with respect to the existence of the H-dibaryon.

Speaker: Juan Fernandez-de la Garza (University of Bern)

17:30 The fate of Hybrid Charmonium at finite temperature

We report on the progress of our calculation of the $1^{-+}$ exotic charmonium hybrid state at finite temperature using anisotropic FASTSUM ensembles. Using a wide basis of operators proposed by the Hadron Spectrum Collaboration together with optimal distillation profiles, we extend our existing spectrum results at different temperatures below and above $T_c$ to include zero-temperature ones. The use of distillation profiles allows us to circumvent the limitation in number of operators brought by finite temperature at very little additional cost. Finally, we use the zero-temperature results to study the change of the spectral function of the hybrid via the reconstructed correlator method, improving on our previously presented results which were still affected by unwanted finite-temperature systematic effects.

Speaker: Juan Andres Urrea Nino (Trinity College Dublin)

16:10 → 17:50 QCD at nonzero temperature and density

Convener: Etsuko Itou

16:10 Testing strong isospin breaking effects in QCD thermodynamics

Most modern lattice QCD calculations take the masses of the light quarks to be degenerate, setting $m_u=m_d$, a choice that, while not exactly physical, increases computational efficiency and lowers the complexity of simulations and analysis. For many observables, the systematic error associated with this simplification is expected to be negligible, as $\Delta m_{ud}=m_d-m_u$ is significantly below the QCD scale. So far lattice studies have examined the role of strong isospin breaking (SIB) in hadron mass splittings, but SIB effects in thermodynamic observables have only been studied in terms of the transition temperature with unphysically heavy quarks. Motivated by the recent observation of an unexpectedly large ratio between the abundances of charged versus neutral kaons in heavy-ion collisions experiments, we investigate the effects of SIB in QCD by computing thermodynamic observables with $N_f=1+1+1$ and with physical quark masses using dynamical improved staggered fermions. In particular, we investigate the difference between the $u$- and $d$-quark condensates and extract the pseudocritical temperature, the equation of state, and conserved-charge fluctuations, comparing results to standard $N_f=2+1$ simulations.

Speaker: David Clarke

16:30 The onset of the QCD conformal window from chiral phase boundaries

Once the number of massless fermions exceeds a critical value $N_f^*$, many-flavour QCD enters the conformal window, where chiral symmetry remains intact in the vacuum. In lattice simulations the theory can only be probed at a finite cutoff, finite temporal extent and nonzero quark mass. The latter invariably breaks chiral symmetry and thus one generically observes a thermal chiral transition also for $N_f\geq N_f^*$. For QCD to correspond to an infrared conformal theory, this transition must not be connected to the continuum chiral limit. In this work, we present the chiral phase boundaries of unimproved staggered fermions in the bare lattice parameter space $(N_\tau,\, \beta,\, am,\, N_f)$, focusing on a direct comparison between $N_f=7$ and $N_f=8$. For $N_f=7$, we find that the chiral transition remains present in the continuum chiral limit $(\beta\to\infty, \, N_\tau\to\infty, \, am\to0)$. For $N_f=8$, by contrast, the transition is absent in this limit; instead, the massless continuum theory is chirally symmetric in the vacuum. This suggests that the conformal window opens at $N_f^*=8$.

Speaker: Jan Philipp Klinger (Goethe University Frankfurt)

16:50 Higgs-Confinement Continuity in SU(2) Gauge-Higgs Model with Color-Flavor-Locking Potential

Dense QCD matter is expected to exhibit color-superconducting phases, such as the color-flavor-locked (CFL) phase. In the CFL phase, the color gauge symmetry is Higgsed, and the global $U(1)_B$ baryon-number symmetry is spontaneously broken. An interesting observation is that a hadronic superfluid phase at intermediate densities realizes the same pattern of global symmetry breaking. This motivates the conjecture of quark–hadron continuity, namely that the hadronic superfluid and CFL phases may be smoothly connected without a thermodynamic phase transition. Because direct lattice simulations of dense QCD suffer from the sign problem, gauge–Higgs models with analogous symmetry structures provide useful laboratories for studying this question.

In this work, we study a two-color, two-flavor $SU(2)$ gauge–Higgs model with a color–flavor-locking potential. The Higgs field carries both color and flavor indices, and the potential favors a color–flavor-locked configuration. This model possesses a global $U(1)$ symmetry analogous to the baryon-number symmetry in QCD, and its $U(1)$-broken phase contains both confinement and Higgs(CFL) regimes. We investigate the phase diagram of this model and Higgs–confinement continuity in the $U(1)$-broken phase. This study serves as a tractable lattice approach to quark–hadron continuity in QCD through the corresponding Higgs–confinement continuity in a gauge–Higgs model.

Speaker: Yusuke Shimada (YITP, Kyoto University)

17:10 Dimensional Decomposition of Eigenstates in Chiral Anderson Models

We apply the recently-developed technique of dimensional decomposition to eigenstates of chiral Anderson models. This approach provides the complete information on effective dimensions present in a spatial structure. We focus on the class of orthogonal models with logarithmic disorder in 3D, that bear interesting similarities to QCD in IR phase at the level of spectral densities.

Speaker: Navdeep Singh Dhindsa (TIFR Mumbai)

17:30 IR Phase of QCD and Chiral Anderson Models

The IR phase of thermal QCD is characterized, among other things, by power singularity of Dirac spectral density at zero (power near -1), and by an unusual pattern of IR spatial dimensions. The first aspect has also been proposed for density of states in chiral orthogonal Anderson models with off-diagonal logarithmic disorder. Here we identify the root cause and the precise form of that similarity, and investigate whether the likeness also extends to the associated dimensional structures.

Speaker: Ivan Horvath (Nuclear Physics Institute, Řež-Prague, Czech Republic)

16:10 → 17:50 Quark and lepton flavor physics

Convener: William Jay (Colorado State University)

16:10 Leveraging Existing HISQ Eigenvectors for Improved Statistical Precision in the HVP Contribution to muon g-2

The low-mode contribution to the hadronic vacuum polarization dominates the total statistical error, making its efficient computation a critical bottleneck in lattice QCD determinations of the muon anomalous magnetic moment. We present and validate a strategy that leverages already available Fermilab Lattice/HPQCD/MILC HISQ eigenvectors to improve the statistics of our existing fat link calculation without generating new eigenvectors (except a small number for bias correction). Using the decomposition $D_{HISQ} = D_{Fat} + D_{Naik}$ for the HISQ Dirac operator, fat-link correlators are reconstructed from the known HISQ eigensystem at negligible, or no additional cost. We use an AMA-style bias correction computed on a small set of configurations to eliminate the systematic difference between the two actions. We demonstrate the method on a $48^3$, a=0.12 fm ensemble and then turn to the application of the method to a larger $144^3$, a=0.042 fm ensemble. Both ensembles are from the MILC collaboration.

Speaker: Vaishakhi Moningi (University of Connecticut)

16:30 Isospin-breaking effects in inclusive hadronic tau data for the muon (g-2)

In this presentation we discuss a strategy to use experimental data from hadronic tau decays for the Hadronic-Vacuum-Polarization contribution to the muon anomalous moment. Having a model-independent determination of the corresponding isospin-breaking effects has been recently highlighted as a priority in the last White Paper. Here we present a strategy for their calculation from Lattice QCD+QED simulations, discussing both the short-distance renormalization in the context of momentum schemes and the long-distance effects.
By giving a prescription for the separation between factorizable and non-factorizable radiative corrections, we can calculate the difference between the neutral and charged channels, the most pressing theoretical input identified by the g-2 theory initiative.

Speaker: Mattia Bruno (Universita' di Milano-Bicocca)

16:50 The smeared R-ratio in isospin symmetric QCD from first-principles lattice simulations

The R-ratio is a phenomenologically important observable, relevant both in its own right and in applications such as the dispersive approach to the muon anomalous magnetic moment. A first-principles lattice QCD investigation of the R-ratio can be carried out with controlled statistical and systematic uncertainties, by introducing a suitable energy-smearing kernel and employing spectral reconstruction techniques, such as the Hansen-Lupo-Tantalo algorithm. Building on our first study published in 2023, we present preliminary results using the correlation functions produced by ETMC in Nf=2+1+1 lattice simulations at four lattice spacings, different volumes and with higher statistics than in our previous work. The new correlators, thanks to the implementation of the Low Mode Averaging technique, allow the determination of the R-ratio smeared with Gaussian kernels of widths down to σ∼200 MeV with phenomenologically relevant precision.

Speaker: Francesca Margari (University of Rome Tor Vergata)

17:10 Inclusive $\bar B_s\to X_{\bar sc} \ell \bar \nu$ decay from lattice QCD

Inclusive semileptonic decays of $B$ mesons play a central role in flavour physics, as they provide stringent tests of the Standard Model. These processes can now be studied from first principles using lattice QCD simulations combined with spectral reconstruction techniques. In this talk, we present the first non-perturbative calculation at physical point of the decay rate for the inclusive process $\bar B_s\to X_{\bar sc}\ell\bar\nu$. The calculation is performed using state-of-the-art ETMC gauge ensembles and includes a continuum extrapolation based on three lattice spacings. We employ the Hansen-Lupo-Tantalo method to extract the decay rate directly from Euclidean correlation functions with controlled uncertainties. This study enables the first determination of $|V_{cb}|$ from inclusive semileptonic decays using lattice QCD. By combining our result with the corresponding Belle experimental measurement, we obtain $|V_{cb}|$ with an overall precision of about 8\%, representing a significant step toward resolving the long-standing $|V_{cb}|$ puzzle. The present precision is expected to improve significantly with the inclusion of a fourth lattice spacing and increased statistics, both of which are currently underway.

Speaker: Alessandro De Santis (Helmholtz-Institut Mainz, Johannes Gutenberg-Universität Mainz)

17:30 Gradient flow and heavy-light physics

Gradient flow (GF) is a powerful concept to calculate important quantities in heavy flavor physics on the lattice. We showcase two examples:

First we demonstrate using GF to obtain matching factors for heavy-light currents fully nonperturbatively. This addresses the challenge that due to the large mass difference matching factors for a "mixed action setup" are often required. GF provides a procedure to also obtain the needed correction factor $\rho$ nonperturbatively.

Secondly, we present our results to determine bag-parameters describing neutral meson mixing or heavy meson lifetimes using GF in combination with the short-flow-time expansion (SFTX).

Speaker: Oliver Witzel (University of Siegen)

16:10 → 17:30 Structure of hadrons and nuclei

Convener: Raza Sufian (New Mexico State University / BNL)

16:10 Portraits of Charmoniumlike States

We carry out the first lattice calculation of the charm quark density-density correlations for $1S$ and $1P$ conventional charmonia, as well as charmoniumlike states $\eta_{c1}(1^{-+})$ and $h_{c0}(0^{+-})$, which provide {\it ab initio} information about the internal spatial structures of these states. The spatial distributions of the charm quark and antiquark ($c\bar{c}$) in $1S$ and $1P$ states exhibit clear relativistic effects that can be understood neatly in the Dirac theory of quarks with a Cornell-type potential. For the charmoniumlike hybrid $\eta_{c1}(1^{-+})$ and $h_{c0}(0^{+-})$, the $c\bar{c}$ component is compact with a spatial size comparable with those of charmonia. Specifically, $\eta_{c1}$ can be viewed as an $S$-wave bound state of a color octet $1^{--}$ $c\bar{c}$ component and a $1^{+-}$ gluonic (chromomagnetic) component. The calculation is performed in $N_f=2$ lattice QCD with a pion mass around 420~MeV and at a single lattice spacing of about 0.136(2) fm. The systematic uncertainties should be investigated through more sophisticated lattice setups in the future.

Speaker: Geng Li

16:30 Radiative decays of charmonia

Over the past decades a number of resonances have been discovered, mostly in the charm sector, that do not fit into a simple quark model picture. A rigorous understanding of how these states arise from QCD and how they can be classified is required, which can only be attained in conjunction with advances in the calculational methods.

In addition to the study of masses and widths of stable hadrons and hadronic resonances, more detailed information on the structure of hadrons can be obtained from radiative transitions and electromagnetic form factors, which are related to a hadron’s coupling to a photon. This is a first step before looking at exotic states (i.e. states that do not fit the simple quark model).

The aim of our project is to take the successful and well tested method of distillation with optimised profiles, which enables the construction of interpolating operators with increased overlap to the desired states, and further develop and implement the method for computing 3-point functions, and from these form factors. We aim to look at the radiative transitions between higher lying states, with preliminary results on $J/\psi \to \eta_c\gamma$. These simulations were done on a $n_f=3+1$ ensemble denoted A1, with pion mass $m_\pi\approx 420$ MeV and lattice spacing $a\approx 0.052$ fm.

Speaker: Jonna Marjaana Koponen (Bergische Universität Wuppertal)

16:50 Update on the calculation of the long-distance $\pi^0$ exchange part of the hadronic light-by-light (HLbL) contribution to muon g-2 from RBC-UKQCD.

We will provide an update to the RBC-UKQCD collaborations on the lattice calculation of the position-space, long-distance $\pi^0$ exchange part of the HLbL contribution to the anomalous magnetic moment of the muon. We will present the results of the calculation from 48I and 64I gauge-field ensembles at $a^{-1}=1.73$ GeV and $a^{-1}=2.359$ GeV, respectively. Additionally, we will present the comparison of the above results with the model calculations of the $\pi^0$ exchange contribution and the long-distance part of the pion-pole contribution, both based on the Lowest Meson Dominance (LMD) model for the $\pi^0$ transition form factor.

Speaker: Anton Shcherbakov

17:10 Hadron structure from Hamiltonian lattice gauge theory with tensor networks

The rich internal structure of hadrons is encoded in partonic functions, such as parton distribution functions (PDFs) and light-cone distribution amplitudes (LCDAs), which are crucial in collider experiments and decay processes. Calculating them from first principles remains a major challenge: they require matrix elements with a Wilson line along a light-like direction, which are not directly accessible in the Euclidean lattice formulation underlying conventional Monte Carlo simulations. In contrast, the Hamiltonian formalism allows for a direct treatment of light-cone dynamics. Recent developments allow to simulate states in Hilbert space efficiently with tensor networks or quantum devices. We present a framework to extract light-cone matrix elements in Minkowski space and demonstrate the approach in the massive Schwinger model. Our tensor-network calculations led to PDFs and LCDAs of the Schwinger model for different fermion masses with controlled uncertainties, demonstrating the feasibility of tensor networks for dynamical calculations in gauge theories.

Speaker: Manuel Schneider (National Yang Ming Chiao Tung University)

16:10 → 17:30 Theoretical developments and applications beyond the SM

Convener: Antonio Smecca (INFN - Sezione di Roma Tre)

16:10 Gravitational waves from the confinement transition in the one-flavor SU(4) Hyper Stealth Dark Matter

We report on the gravitational wave spectrum study from the confinement transition in the one-flavor SU(4) Hyper Stealth Dark Matter theory. We use the multihistogram method to construct the Polyakov loop effective potential in the complex plane, from which the order of transition as well as the tunneling rate is obtained. This method allows us to study the gravitational wave spectrum down to the second-order point, where the sea-quark effect becomes relevant. The decrease in the surface tension due to the sea quarks leads to a decrease in the amplitude of the gravitational waves.

This talk is based on arXiv:2602.23002 [hep-lat].

Speaker: Nobuyuki Matsumoto (Boston University)

16:30 Quenched glueball and meson spectrum in the 't Hooft limit of lattice Yang-Mills theories

The study of large-$N$ Yang-Mills theories is theoretically interesting because of the many mathematical simplifications that appear when the rank of the gauge group goes to infinity, and the dynamics of such theories is conjectured to be key to tackle other open problems such as the confinement mechanism. We report on the advancements in our efforts to compute the Glueball and Meson spectra in the 't Hooft limit of $SU(N)$ Yang-Mills theory. We employ a 2-level sampling algorithm for the computation of glueball correlators between operators corresponding to spatial Wilson loops at different levels of (APE) smearing. The Multilevel approach allows to mitigate the signal-to-noise-ratio problem in the long time separation region and produce more stable and recognizable plateaux. We also report on the results for the meson spectrum, introducing in our basis operators with overlap on spin $> 1$ states.

Speaker: Andrea Falzetti ("Sapienza" University of Rome)

Saturday 1 August

09:00 → 10:30 Plenary session

Convener: Anna Hasenfratz

09:00 Recent results in lattice BSM

I will review recent results in lattice BSM with updates on composite Higgs, dark matter, supersymmetry, lattice gravity and chiral fermions. I will also describe new ideas such as symmetric mass generation and lattice anomalies.

Speaker: Simon Catterall (Syracuse University)

09:45 Gradient Flow in Lattice QCD: Recent Applications and Developments

The gradient flow has become a powerful and versatile tool in lattice QCD calculations. At positive flow time, gauge and fermion fields are smoothed over a physical radius of order $\sqrt{t}$, providing an additional ultraviolet regulator that can simplify the construction and analysis of lattice observables. Physical quantities are then recovered by combining continuum extrapolations at fixed flow time with suitable procedures to connect flowed observables to the vanishing-flow-time limit.

In this talk I will review selected recent applications and developments of the gradient flow in lattice QCD. I will discuss the properties of flowed fields that are most relevant for current applications, with particular emphasis on the construction, normalization, and matching of flowed composite local operators. I will then discuss representative examples where the gradient flow has been used to define lattice observables that are difficult to access with standard approaches, or where its use has provided promising advantages compared with standard techniques. I will conclude with perspectives on the role of flow time as a physical scale and on the relation between flowed quantities and conventional continuum schemes.

Speaker: Andrea Shindler

10:30 → 11:00 Coffee break

11:00 → 13:00 Plenary session

Convener: Stephen Sharpe (University of Washington)

11:00 Dealing with left-hand cuts in multi-hadron spectroscopy

Multi-hadron spectroscopy from lattice QCD commonly relies on Lüscher-type finite-volume methods to extract infinite-volume scattering amplitudes from discrete energy levels. While highly successful for short-range interactions, standard analyses based on this strategy can become problematic when light-particle exchange generates nearby left-hand cuts.

In this talk, I will review recent approaches to this problem, including finite-volume EFT and plane-wave method, modified Lüscher formalism, modified effective-range expansion, relativistic three-body field-theory formalisms and finite-volume N/D methods. Applications to $T_{cc}$, $D D^\ast$, $D D\pi$, dibaryon systems, and the $H$-dibaryon will be discussed, together with recent progress toward understanding the relations among these frameworks.

Speaker: Lu Meng (Southeast University)

11:30 Benchmarking lattice determinations of x-dependent hadron structure

The determination of x-dependent hadron structure from lattice QCD is an increasingly mature endeavour; precision calculations, with control over all systematic uncertainties, hover on the horizon. Precise and accurate lattice calculations will complement the experimental data expected from JLab 12GeV and the future Electron-Ion Collider and shed new light on the internal structure of hadrons. To achieve that goal, however, requires careful analysis of systematic uncertainties in lattice calculations. We propose “window observables” as a quantitative approach to precision benchmarking and cross-validation between and within lattice calculations and global analyses. I will review and motivate two potential window observables and discuss their application to the quark transversity distribution and beyond.

Speaker: Christopher Monahan

12:00 The axion-photon coupling from lattice QCD

Axions were first proposed as a solution to the strong CP problem, but they also act as prime dark matter candidates. Detection of axions hinges on their conversion to photons, governed by the axion-photon coupling. Besides the direct, modeling dependent part, coupling can be realized through sea effects of the strong interaction. The value of the latter can be calculated directly from QCD. We present the first non-perturbative determination of this contribution, employing CP violating background electromagnetic fields. We also discuss a novel method to estimate the topological charge based on the axial Ward identity. We obtain $g_{a\gamma\gamma}= -1.77(8)\alpha/(2\pi f_a)$, which is about 10% smaller in magnitude than and is in some tension with the ChPT prediction quoted by the PDG.

Speaker: Mr Gergely Marko (Eotvos Lorand University, Institute of Physics)

12:30 Lattice 2027 teaser

12:45 Closing remarks

Speaker: Prof. Zohreh Davoudi (University of Maryland)

13:00 → 14:00 Lunch break (boxed lunch)