Dynamical Simulations with Highly Improved Staggered Quarks

TL;DR

This paper presents a general iterative method for computing the fermion force in lattice QCD simulations with highly improved staggered quark actions, enabling more accurate and efficient dynamical simulations.

Contribution

It introduces a versatile iterative procedure for deriving the fermion force for actions with arbitrary smearing and reunitarization, applicable to advanced lattice QCD actions.

Findings

The method is applicable to actions with various smearing levels.

Calculating the HISQ force is roughly twice as costly as the ASQ force.

The approach enhances the accuracy and efficiency of dynamical lattice QCD simulations.

Abstract

It is well established that lattice artifacts can be suppressed substantially by the use of SU(3)-projected smeared links in the fermion action. An example is the Highly Improved Staggered Quark action where the ASQ-like effective links are constructed from reunitarized Fat7 links. A general procedure is presented for computing the derivative of the fermion action with respect to the base links (fermion force) - a key component in dynamical simulations using molecular dynamics evolution. The method is iterative and can be applied to actions with arbitrary levels of smearing and reunitarization. The cost of calculating the fermion force is determined for the ASQ action and the HISQ action. Test results show that calculating the HISQ force is about two times more expensive than the ASQ force.