Step scaling with gradient flow and finite temperature

TL;DR

This paper develops a method combining gradient flow, step-scaling, and finite-temperature boundary conditions to accurately scale 2+1+1 flavor QCD lattices across multiple spacings, enabling precise topological susceptibility calculations at high temperatures.

Contribution

It introduces a novel approach integrating gradient flow and step-scaling for finite-temperature lattice QCD with physical quark masses.

Findings

Achieved lattice spacings down to 0.01378 fm with controlled temperature and quark mass matching.

Prepared the framework for continuum extrapolation of topological susceptibility at high temperatures.

Ensured percent-level temperature and a few percent quark mass consistency across lattices.

Abstract

We combine gradient flow, step-scaling, and finite-temperature boundary conditions to scale-set 2+1+1 flavor QCD lattices with physical HISQ quarks at multiple spacings down to a=0.01378 fm, such that they represent the same temperature at the percent level and the same quark mass to a few percent. This preparatory work will allow the evaluation and continuum extrapolation of the topological susceptibility at up to 1 GeV temperatures with good control over quark-mass effects.