Two-flavor lattice QCD simulation in the epsilon-regime with exact chiral symmetry

TL;DR

This paper reports on lattice QCD simulations with exact chiral symmetry in the epsilon-regime, confirming theoretical predictions and extracting the chiral condensate with high precision.

Contribution

It demonstrates the feasibility of simulating two-flavor QCD with exact chiral symmetry in the epsilon-regime and validates the Dirac eigenvalue spectrum against chiral random matrix theory.

Findings

Dirac eigenvalue spectrum agrees with chiral random matrix theory

Chiral condensate measured as (251(7)(11) MeV)^3

Simulation achieved at light quark mass of 3 MeV

Abstract

We perform lattice simulations of two-flavor QCD using Neuberger's overlap fermion, with which the exact chiral symmetry is realized at finite lattice spacings. The epsilon-regime is reached by decreasing the light quark mass down to 3 MeV on a 16^3 32 lattice with a lattice spacing \sim 0.11 fm. We find a good agreement of the low-lying Dirac eigenvalue spectrum with the analytical predictions of the chiral random matrix theory, which reduces to the chiral perturbation theory in the epsilon-regime. The chiral condensate is extracted as \Sigma(2 GeV) = (251(7)(11) MeV)^3, where the errors are statistical and an estimate of the higher order effects in the epsilon-expansion.