Domain wall fermions with improved gauge actions

TL;DR

This paper demonstrates that using improved gauge actions like DBW2 significantly reduces residual chiral symmetry breaking in quenched domain wall fermions, leading to more accurate lattice QCD simulations.

Contribution

The study shows that improved gauge actions substantially suppress residual chiral symmetry breaking in domain wall fermions, especially with the DBW2 action, compared to the Wilson action.

Findings

Residual quark mass is two orders of magnitude smaller with DBW2 at certain lattice spacings.

Improved gauge actions reduce topological lattice dislocations.

Enhanced numerical results for light hadron spectrum and pion decay constant with DBW2.

Abstract

We study the chiral properties of quenched domain wall fermions with several gauge actions. We demonstrate that the residual chiral symmetry breaking, which is present for a finite number of lattice sites in the fifth dimension ($L_s$), can be substantially suppressed using improved gauge actions. In particular the Symanzik action, the Iwasaki action, and a renormalization group improved gauge action, called doubly blocked Wilson (DBW2), are studied and compared to the Wilson action. All improved gauge actions studied show a reduction in the additive residual quark mass, $\mres$. Remarkably, in the DBW2 case $\mres$ is roughly two orders of magnitude smaller than the Wilson gauge action at $a^{-1}=2$ GeV and $L_s=16$. Significant reduction in $\mres$ is also realized at stronger gauge coupling corresponding to $a^{-1}=1.3$ GeV. As our numerical investigation indicates, this reduction is achieved by reducing the number of topological lattice dislocations present in the gauge field configurations. We also present detailed results for the quenched light hadron spectrum and the pion decay constant using the DBW2 gauge action.