The running coupling in lattice Landau gauge with unquenched Wilson fermion and KS fermion

TL;DR

This study measures the running coupling and quark propagator in lattice Landau gauge QCD with unquenched Wilson and KS fermions, revealing infrared suppression and effects of condensates at a few GeV$^2$.

Contribution

It provides the first combined analysis of Wilson and KS fermion effects on the running coupling and quark propagator in unquenched lattice Landau gauge QCD.

Findings

Infrared suppression of the KS fermion quark propagator.

Effects of $A_^2$ condensates observed at a few GeV$^2$.

Renormalization factors define the quark wave function scale.

Abstract

The running coupling of the Wilson fermon(JLQCD/CP-PACS) and that of Kogut-Susskind(KS) fermion(MILC) are measured in the lattice Landau gauge QCD in $\widetilde{MOM}$ scheme. The quark propagator of the KS fermion is also measured and we find that it is infrared suppressed. The renormalization factor of the running coupling and the tadpole renormalization define the scale of the quark wave function. Effects of the $A_\mu^2$ condensates of a few GeV$^2$ are observed in the running coupling and also in the quark propagator.