Quark chiral condensate from the overlap quark propagator

TL;DR

This paper determines the quark chiral condensate using lattice QCD calculations of the overlap quark propagator, fitting to operator product expansion formulas, and provides a precise value in the SU(2) chiral limit.

Contribution

It introduces a method to extract the quark chiral condensate from lattice data using overlap fermions and OPE fits, with results on multiple ensembles at fixed lattice spacing.

Findings

Quark condensate value in the SU(2) chiral limit: (-305(15)(21) MeV)^3.

Use of overlap fermions and OPE fitting on RBC-UKQCD configurations.

Consistent results across different light sea quark masses.

Abstract

From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with $N_f=2+1$ flavors. Three ensembles with different light sea quark masses are used at one lattice spacing $1/a=1.75(4)$ GeV. We obtain $\langle\bar\psi\psi\rangle^{\overline{\rm MS}}(2\mbox{ GeV})=(-305(15)(21)\mbox{ MeV})^3$ in the SU(2) chiral limit.