Heavy quark momentum diffusion from the lattice using gradient flow

TL;DR

This paper introduces a lattice QCD method using gradient flow to accurately compute the heavy quark momentum diffusion coefficient, improving precision and applicability to dynamical fermion actions.

Contribution

The study develops a novel gradient flow technique for lattice calculations of the heavy quark diffusion coefficient, with enhanced extrapolation methods and spectral reconstruction.

Findings

Continuum correlator at zero flow time agrees with previous multi-level results.

High-precision lattice data for the correlator was obtained.

Method applicable to actions with dynamical fermions.

Abstract

We apply the gradient flow on a color-electric two-point function that encodes the heavy quark momentum diffusion coefficient. The simulations are done on fine isotropic lattices in the quenched approximation at $1.5\,T_c$. The continuum extrapolation is performed at fixed flow time followed by a second extrapolation to zero flow time. Perturbative calculations of this correlation function under Wilson flow are used to enhance the extrapolations of the non-perturbative lattice correlator. The final estimate for the continuum correlator at zero flow time largely agrees with one obtained from a previous study using the multi-level algorithm. We perform a spectral reconstruction based on perturbative model fits to estimate the heavy quark momentum diffusion coefficient. The approach we present here yields high-precision data for the correlator and is also applicable for actions with dynamical fermions.