We report on our ongoing lattice QCD computation of antistatic-antistatic-light-light potentials using the CLS $N_f=2$ gauge con๏ฌgurations and the OpenQ*D codebase. We improve on previous work by calculating the correlation matrices for all three attractive ground state potentials previously characterized, to mitigate excited state contributions and further probe the vague indication of...
Centre vortices have been shown to underpin confinement and dynamical chiral symmetry breaking. Here we consider the centre vortex geometry of dynamical QCD at finite temperature using the anisotropic FASTSUM ensembles and uncover evidence for two transition temperatures. The first corresponds to the established chiral transition $T_c$ while the second occurs at $T_d\simeq 2\,T_c$. Drawing...
The covariant coordinate space (CCS) method for hadronic vacuum polarization calculations has been developed as an alternative to the established time-momentum representation (TMR) and is particularly promising for its potential to mitigate statistical noise. Our investigations further reveal that this framework exhibits a favorable continuum limit. We provide an extensive analysis of the...
We construct an exact dual formulation of pure SU(N) Hamiltonian lattice gauge theory with local dual dynamics in (2+1) dimensions. The dual model is obtained by making a series of iterative canonical transformations on the electric field operators and their conjugate vector potentials associated with the links around each plaquette. This transformation maps the original gauge degrees of...
We present an analysis of deflation and low-mode averaging techniques applied to two- and three-point correlation functions of mesons and baryons at the physical point. The focus is on improving the signal quality at large Euclidean time separations, where statistical noise typically dominates. We quantify the computational cost and statistical gains across several ensembles, identifying the...
In theories with topological sectors, such as lattice QCD and four-dimensional SU(N) gauge theories with periodic boundary conditions, conventional update algorithms suffer from topological freezing due to large action barriers separating distinct sectors. With appropriately constructed bias potentials, Metadynamics and related enhanced sampling techniques can mitigate this problem and...
Recent advances in numerical algorithms for matrix function evaluations have significantly improved the stability and efficiency of large-scale computations in quantum field theory. In this study, we investigate their applicability to the calculation of the quark propagator in lattice QCD. The quark propagator, which involves the inversion and functional evaluation of large sparse matrices...
For nearly two decades, the highly improved staggered quark (HISQ) discretization of the Dirac operator has enabled fast and accurate simulations of (2+1)- and (2+1+1)-flavor QCD, particularly at the physical point. Over this period, numerous code bases targeting both CPU and GPU architectures have implemented HISQ through a variety of methods that optimize for low communication overhead,...
We present initial results for the application of a novel relativistic heavy-quark action in the charm sector on 2+1-flavor lattice ensambles produced by the CLS consortium. The five parameter action was tuned non-perturbatively using a neural network and experimental continuum charmonium ground state masses. We investigate effective masses of $D$ meson correlators produced on CLS ensambles...
In this work, we investigate discretization effects proportional to the quark mass, $O(a m)$, on the QCD beta-function within lattice perturbation theory. Using the background field method and improved lattice actions, we compute the renormalization factor of the coupling constant and thus determine the beta-function. In this framework, we calculate, up to two-loop order, the contributions...
Despite their simplicity, O(N) scalar field theories, or O(N) models for short, allow for the investigation of several interesting phenomena such as asymptotic freedom and spontaneous symmetry breaking. On the lattice, O(N) models can be represented in terms of integer-valued flux variables, which allow for efficient Monte Carlo (MC) simulations both at zero and non-zero densities with a worm...
In two dimensions, the phi4 theory exhibits a non-trivial infrared fixed
point that governs the continuum limit and connects to the Ising universality class. I will present the investigation of RG flow of 2D phi4 theory using gradient flow techniques, with smooth lattice configurations and allow for a non-perturbative definition of scale-dependent observables. By tracking the evolution of...
We study the phase diagram of massless staggered fermions with two distinct four-fermion couplings, U and Uโฒ, on a three-dimensional Euclidean lattice using the fermion-bag Monte Carlo method. The model exhibits three distinct phases: a massless fermion phase, a symmetry-broken massive phase with a fermion bilinear condensate, and a symmetric massive phase where fermions acquire mass without...
We present results from our DEI surveys conducted in 2023 and 2024, focusing on whether workshops should be held online or in person. Surprisingly, we find no correlation between diversity criteria and a preference for online conferences, including care responsibilities. The only numerically significant predictors that lead scientists to prefer an online conference, as shown in new survey data...
The sensible application of the Hybrid Monte Carlo (HMC) method to the Hubbard model is hindered by the emergence of infinite potential barriers due to a vanishing fermion determinant, resulting in an ergodicity problem that needs to be resolved. This can be achieved by augmenting the HMC algorithm with radial updates, which refer to multiplicative Metropolis-Hastings updates in a radial...
We present results on the pion and kaon decay constants determined on a set of over 50 coordinated lattice simulations (CLS) gauge ensembles with $N_f=2+1$ sea quark flavours of non-perturbatively improved Wilson fermions. This is part of a project to explore the range of validity of SU(3) chiral perturbation theory (ChPT) in the meson sector and to determine its low energy constants (LECs)....
The conjugate gradient is the standard technique for computing propagators in lattice QCD. Preconditioning the Dirac Operator makes this method faster. The goal of our project is to develop Neural Networks to predict preconditioners for the Dirac operator with the gauge configuration as input.
Our approach closely follows recent successes from MIT[1], where traditional neural networks have...
The sign problem is a major obstacle for lattice studies of spontaneous supersymmetry breaking (SSB). Quantum computing provides a promising alternative approach. In particular, properties of supersymmetry relate SSB to the ground-state energy, which can be probed using hybrid quantum-classical algorithms such as the variational quantum eigensolver (VQE). I will present VQE analyses for...
We present numerical results of staggered fermions with a
taste splitting mass term on dynamical configurations. The rise of gluonic counterterms from rotational symmetry breaking is studied for a single taste operator and the pion propagator is computed. Preliminary numerical results are given for lattice sizes up to $16^4$
We use variational methods to numerically study the matrix model for two-color QCD coupled to a single quark (matrix-QCD(_{2,1})) in the ultra-strong Yang--Mills coupling ((g = \infty)). The model's spectrum is divided into superselection sectors characterized by baryon number (B) and spin (J). Our analysis focuses on the sectors (B = 0, 1, 2) and (J = 0, 1), which correspond to...
The complex Langevin method (CLM) is a promising tool to address the sign problem in quantum field theories with complex actions. However, it can converge to incorrect results even when simulations appear stable, highlighting the need for robust diagnostics. Existing checks, such as monitoring drift distributions, are useful but indirect. We propose a complementary test based on the...
We study the theta dependence of the deconfining temperature in SU(3) Yang-Mills theory. Simulation at real theta causes the sign problem, while simulations at imaginary theta are feasible but suffer from topological freezing that becomes severe at large imaginary theta. We mitigate the topological freezing using two-dimensional parallel tempering technique with replica exchanges across...
Accurately simulating long-time dynamics of quantum many-body systemsโwhether in real or imaginary timeโis a challenge in both classical and quantum computing due to the accumulation of Trotter errors. While low-order Trotter-Suzuki decompositions are straightforward to implement, their rapidly growing error limits access to long-time observables and ground state properties. I will present a...
We present recent progress towards continuum estimates of cumulants of conserved charges in (2+1)-flavor QCD with Mรถbius Domain Wall fermions (MDWF). Simulations are performed at the physical quark-mass point on lattices with temporal extent $N_\tau=12,16$ and aspect ratio $N_{\sigma}/N_{\tau}=3$, enabling a controlled study of cutoff effects. We focus on second- and fourth-order cumulants of...
The Ising model serves as a model for simple magnetic systems and as a testing ground for the study of strongly-coupled systems. The model is exactly solvable in two dimensions and can be simulated with relatively small computing resources. We investigate the phase transition of the Ising model through a novel scaling procedure first proposed to explore the phase structure of a theory with...
Normalizing flows provide a framework to learn statistically exact machine-learned maps between different lattice field theories. Flows constructed to map from QCD to the same theory with a (possibly localized) operator insertion provide a general tool to construct unbiased reduced-variance estimators for lattice QCD correlation functions. Building on previous applications to Feynman-Hellmann...
