Determination of the chiral condensate from 2+1-flavor lattice QCD

TL;DR

This paper presents a precise lattice QCD calculation of the 2+1-flavor chiral condensate using overlap quarks, matching eigenvalue spectra with chiral perturbation theory to achieve accurate results.

Contribution

It introduces a novel method of determining the chiral condensate by combining lattice QCD with eigenvalue spectrum analysis in the epsilon-regime.

Findings

Chiral condensate value: 242(4)(+19-18) MeV^3 at 2 GeV

Successful matching of eigenvalue spectrum with chiral perturbation theory

Precise determination of the condensate with controlled errors

Abstract

We perform a precise calculation of the chiral condensate in QCD using lattice QCD with 2+1 flavors of dynamical overlap quarks. Up and down quark masses cover a range between 3 and 100 MeV on a 16^3x48 lattice at a lattice spacing around 0.11 fm. At the lightest sea quark mass, the finite volume system on the lattice is in the epsilon-regime. By matching the low-lying eigenvalue spectrum of the Dirac operator with the prediction of chiral perturbation theory at the next-to-leading order, we determine the chiral condensate in 2+1-flavor QCD with strange quark mass fixed at its physical value as Sigma (MS-bar at 2 GeV) = [242(04)(^+19_-18}) MeV}]^3, where the errors are statistical and systematic, respectively.