The epsilon regime with Wilson fermions

TL;DR

This paper investigates how Wilson fermions' explicit chiral symmetry breaking affects mesonic correlators in the epsilon-regime, extending chiral perturbation theory to account for lattice spacing effects and analyzing their significance.

Contribution

It generalizes the epsilon-expansion of continuum ChPT to nonzero lattice spacings, providing a framework to quantify lattice artifacts in mesonic correlators.

Findings

Lattice spacing effects are suppressed at typical quark masses.

Corrections become significant at smaller quark masses.

Fits to lattice data show these corrections are small.

Abstract

We study the impact of explicit chiral symmetry breaking of Wilson fermions on mesonic correlators in the epsilon-regime using Wilson chiral perturbation theory (WChPT). We generalize the epsilon-expansion of continuum ChPT to nonzero lattice spacings for various quark mass regimes. It turns out that the corrections due to a nonzero lattice spacing are highly suppressed for typical quark masses of the order aLambda_QCD^2. The lattice spacing effects become more pronounced for smaller quark masses and lead to non-trivial corrections of the continuum ChPT results at next-to-leading order. We compute these corrections for the standard current and density correlation functions. A fit to lattice data shows that these corrections are small, as expected.