Towards dynamical simulations with the anisotropic HISQ action

TL;DR

This paper advances the development of dynamical anisotropic HISQ lattice ensembles, focusing on tuning parameters and preparing for quarkonium spectral function reconstruction relevant to Quark-Gluon Plasma studies.

Contribution

It introduces methods for tuning anisotropy and lattice spacing in aHISQ ensembles and provides the fermion force expressions needed for dynamical simulations.

Findings

Successful tuning of gauge anisotropy and lattice spacing.

Comparison of different quark anisotropy tuning methods.

Analysis of pion taste splittings at high anisotropies.

Abstract

The primary goal of this project is the reconstruction of quarkonium spectral functions from thermal lattice correlators, relevant for the study of Quark-Gluon Plasma in heavy-ion collisions. To this end, we pursue the generation of fully dynamical anisotropic HISQ (aHISQ) ensembles, aiming at a physical strange quark and a heavier-than-physical light quark mass, corresponding to a 300 MeV continuum pion mass. We report on tuning the gauge anisotropy and the lattice spacing of anisotropic pure gauge ensembles with the tree-level Symanzik-improved action using the gradient flow and compare various tuning schemes. We also discuss the simultaneous tuning of the strange quark mass and the quark anisotropy with aHISQ, using spectrum measurements on quenched ensembles. We compare different ways to tune the quark anisotropy and discuss pion taste splittings for aHISQ at anisotropies up to 8. Finally, we present the expressions for the aHISQ fermion force required for dynamical simulations.