Conveners
Quark and lepton flavor physics
- Andre Walker-Loud (Lawrence Berkeley National Laboratory)
Quark and lepton flavor physics
- Davide Giusti
Quark and lepton flavor physics
- Stefan Meinel (University of Arizona)
Quark and lepton flavor physics
- Luka Leskovec (Jozef Stefan Institute & Faculty of Mathematics and Physics, University of Ljubljana)
Quark and lepton flavor physics
- Balint Toth (University of Wuppertal)
Quark and lepton flavor physics
- Ethan Neil
Quark and lepton flavor physics
- Masaaki Tomii
Quark and lepton flavor physics
- Oliver Witzel (University of Siegen)
Quark and lepton flavor physics
- William Jay (Colorado State University)
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Balint Toth (University of Wuppertal)27/07/2026, 14:007Quark and lepton flavor physicsContributed talk
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.
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Matteo Saccardi (Colorado State University)27/07/2026, 14:206Quark and lepton flavor physicsContributed talk
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...
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Sarah Fields (Columbia University)27/07/2026, 14:402Quark and lepton flavor physicsContributed talk
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...
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Ryan Abbott (Columbia University)27/07/2026, 15:004Quark and lepton flavor physicsContributed talk
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...
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William Jay (Colorado State University)27/07/2026, 15:203Quark and lepton flavor physicsContributed talk
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...
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Christoph Lehner (Universitรคt Regensburg)27/07/2026, 16:109Quark and lepton flavor physicsContributed talk
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...
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Jonas Hildebrand (University of Connecticut)27/07/2026, 16:302Quark and lepton flavor physicsContributed talk
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...
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Masaaki Tomii27/07/2026, 16:503Quark and lepton flavor physicsContributed talk
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...
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Julian Parrino (University of Regensburg)27/07/2026, 17:107Quark and lepton flavor physicsContributed talk
In the current determination of the muon g-2, the hadronic vacuum polarization (HVP) contributionโธบwhich dominates the theoretical uncertaintyโธบis 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...
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Ramรณn Merino (Universidad de Granada)28/07/2026, 14:003Quark and lepton flavor physicsContributed talk
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...
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Takeshi Yamazaki (University of Tsukuba)28/07/2026, 14:202Quark and lepton flavor physicsContributed talk
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...
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Francesco Sanfilippo (INFN Roma Tre)28/07/2026, 14:405Quark and lepton flavor physicsContributed talk
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...
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Andre Walker-Loud (Lawrence Berkeley National Laboratory)28/07/2026, 15:005Quark and lepton flavor physicsContributed talk
I will describe our new lattice action using Mรถbius 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...
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Zack Hall (Lawrence Berkeley National Laboratory)28/07/2026, 15:205Quark and lepton flavor physicsContributed talk
We present a determination for the ratio of light and D meson decay constants in lattice QCD. This work employs a new four flavor Mรถbius 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 $F_{K^{\pm}}/F_{\pi^{\pm}}$ =...
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Norman Christ (Columbia University)28/07/2026, 16:105Quark and lepton flavor physicsContributed talk
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 $\alpha_s$...
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Ceran Hu (Columbia University)28/07/2026, 16:301Quark and lepton flavor physicsContributed talk
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 GlashowโIliopoulosโMaiani (GIM) cancellation. This allows the required...
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Davide Giusti28/07/2026, 16:506Quark and lepton flavor physicsContributed talk
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...
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Alessandro Cotellucci (Forschungszentrum Jรผlich)28/07/2026, 17:103Quark and lepton flavor physicsContributed talk
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...
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Alessandro Conigli29/07/2026, 09:005Quark and lepton flavor physicsContributed talk
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...
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Arnau Beltran (JGU Mainz)29/07/2026, 09:205Quark and lepton flavor physicsContributed talk
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...
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Ethan Neil29/07/2026, 09:401Quark and lepton flavor physicsContributed talk
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...
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Shaun Lahert29/07/2026, 10:003Quark and lepton flavor physicsContributed talk
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...
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Khai Phan (ETH Zurich)29/07/2026, 10:203Quark and lepton flavor physicsContributed talk
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...
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Dominik Erb29/07/2026, 11:104Quark and lepton flavor physicsContributed talk
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...
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Sebastian Lahrtz (Johannes Gutenberg-University Mainz)29/07/2026, 11:303Quark and lepton flavor physicsContributed talk
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...
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David Albandea (Helmholtz-Institut Mainz, GSI)29/07/2026, 11:506Quark and lepton flavor physicsContributed talk
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...
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marco garofalo (University of Bonn, HISKP)29/07/2026, 12:106Quark and lepton flavor physicsContributed talk
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...
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Luka Leskovec (Jozef Stefan Institute & Faculty of Mathematics and Physics, University of Ljubljana)30/07/2026, 14:00Quark and lepton flavor physicsContributed talk
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....
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Junya Tokoro (The University of Osaka)30/07/2026, 14:201Quark and lepton flavor physicsContributed talk
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...
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Antonino D'anna (INSTITUTO DE FISICA TEORICA, UAM-CSIC)30/07/2026, 14:402Quark and lepton flavor physicsContributed talk
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...
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Nicholas Cassar (Colorado State University)30/07/2026, 15:002Quark and lepton flavor physicsContributed talk
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...
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Prof. Stefan Meinel (University of Arizona)30/07/2026, 15:201Quark and lepton flavor physicsContributed talk
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...
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Dr Gregoris Spanoudes (University of Cyprus)30/07/2026, 16:102Quark and lepton flavor physicsContributed talk
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...
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Ryan Kellermann (High Energy Accelerator Research Organization (KEK))30/07/2026, 16:30Quark and lepton flavor physicsContributed talk
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 Mรถbius domain-wall fermions. We obtain results that are in agreement with currently available experimental data, with an error at the...
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Navdeep Singh Dhindsa (TIFR Mumbai)30/07/2026, 16:50Quark and lepton flavor physicsContributed talk
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...
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Akhil Chauhan (University of Illinois Urbana Champaign)30/07/2026, 17:102Quark and lepton flavor physicsContributed talk
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 collaborationโs $2+1+1$-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...
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Vaishakhi Moningi (University of Connecticut)31/07/2026, 16:105Quark and lepton flavor physicsContributed talk
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...
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Mattia Bruno (Universita' di Milano-Bicocca)31/07/2026, 16:303Quark and lepton flavor physicsContributed talk
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...
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Francesca Margari (University of Rome Tor Vergata)31/07/2026, 16:503Quark and lepton flavor physicsContributed talk
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...
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Alessandro De Santis (Helmholtz-Institut Mainz, Johannes Gutenberg-Universitรคt Mainz)31/07/2026, 17:103Quark and lepton flavor physicsContributed talk
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...
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Oliver Witzel (University of Siegen)31/07/2026, 17:301Quark and lepton flavor physicsContributed talk
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...
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