Lattice study of meson correlators in the epsilon-regime of two-flavor QCD

TL;DR

This study computes meson correlators in the epsilon-regime of two-flavor QCD using lattice simulations with exact chiral symmetry, confirming theoretical predictions and extracting key low-energy constants.

Contribution

It provides the first lattice calculation of meson correlators in the epsilon-regime with dynamical overlap fermions, accurately determining F and Sigma.

Findings

Consistent with epsilon-expansion chiral perturbation theory

Extracted pion decay constant F=87.3(5.6) MeV

Determined chiral condensate Sigma^{MS}=[239.8(4.0) MeV]^3

Abstract

We calculate mesonic two-point functions in the epsilon-regime of two-flavor QCD on the lattice with exact chiral symmetry. We use gauge configurations of size 16^3 32 at the lattice spacing a \sim 0.11 fm generated with dynamical overlap fermions. The sea quark mass is fixed at \sim 3 MeV and the valence quark mass is varied in the range 1-4 MeV, both of which are in the epsilon-regime. We find a good consistency with the expectations from the next-to-leading order calculation in the epsilon-expansion of (partially quenched) chiral perturbation theory. From a fit we obtain the pion decay constant F=87.3(5.6) MeV and the chiral condensate Sigma^{MS}=[239.8(4.0) MeV ]^3 up to next-to-next-to-leading order contributions.