Nonperturbative improvement and tree-level correction of the quark propagator

TL;DR

This study improves the lattice Landau gauge quark propagator calculations by implementing nonperturbative corrections and comparing different tree-level correction methods, notably finding the hybrid approach most effective.

Contribution

It introduces a nonperturbative improvement scheme and evaluates three tree-level correction methods, establishing the hybrid approach as the most robust for lattice QCD quark propagator analysis.

Findings

Hybrid correction method is most reliable.

Good agreement with nonperturbative improvement coefficients.

Successful extrapolation of quark mass function to chiral limit.

Abstract

We extend an earlier study of the Landau gauge quark propagator in quenched QCD where we used two forms of the O(a)-improved propagator with the Sheikholeslami-Wohlert quark action. In the present study we use the nonperturbative value for the clover coefficient c_sw and mean-field improvement coefficients in our improved quark propagators. We compare this to our earlier results which used the mean-field c_sw and tree-level improvement coefficients for the propagator. We also compare three different implementations of tree-level correction: additive, multiplicative, and hybrid. We show that the hybrid approach is the most robust and reliable and can successfully deal even with strong ultraviolet behavior and zero-crossing of the lattice tree-level expression. We find good agreement between our improved quark propagators when using the appropriate nonperturbative improvement coefficients and hybrid tree-level correction. We also present a simple extrapolation of the quark mass function to the chiral limit.