Radiative corrections to the lattice gluon action for highly improved staggered quarks (HISQ) and the effect of such corrections on the static potential

TL;DR

This paper calculates how dynamical HISQ fermions affect the radiative corrections to the gluonic action and estimates their impact on lattice scale setting and scaling violations in lattice QCD simulations.

Contribution

It provides a perturbative analysis of fermionic effects on the gluonic action for HISQ fermions, extending previous work on asqtad fermions, and assesses their influence on lattice observables.

Findings

Fermionic contributions to radiative corrections are larger for HISQ than for asqtad.

Omission of these corrections causes a measurable -0.6% shift in (r_1/a) on coarse ensembles.

The results help explain observed scaling violations in lattice QCD data.

Abstract

We perform a perturbative calculation of the influence of dynamical HISQ fermions on the perturbative improvement of the gluonic action in the same way as we have previously done for asqtad fermions. We find the fermionic contributions to the radiative corrections in the Luescher-Weisz gauge action to be somewhat larger for HISQ fermions than for asqtad. Using one-loop perturbation theory as a test, we estimate that omission of the fermion-induced radiative corrections in dynamical asqtad simulations will give a measurable effect. The one-loop result gives a systematic shift of about -0.6% in (r_1/a) on the coarsest asqtad improved staggered ensembles. This is the correct sign and magnitude to explain the scaling violations seen in Phi_B on dynamical lattice ensembles.