Convergence of chiral perturbation theory in dynamical lattice QCD with exact chiral symmetry

TL;DR

This paper investigates how well chiral perturbation theory converges in lattice QCD with exact chiral symmetry, finding convergence issues at the kaon mass scale and extending analysis to include strange quarks with NNLO formulas.

Contribution

It provides the first detailed comparison of lattice QCD data with chiral perturbation theory predictions using overlap fermions, highlighting convergence limitations at certain scales.

Findings

NLO predictions do not converge at the kaon mass scale for Nf=2.

Extended analysis to Nf=2+1 using NNLO formulas improves extrapolation.

Demonstrates the importance of higher-order terms in chiral expansion.

Abstract

We present our recent lattice calculation with dynamical quarks using the overlap fermion formulation, which has exact chiral symmetry. It is possible to compare our data of meson mass and decay constant with the prediction from the chiral perturbation theory. From such comparison, we investigate the convergence property of the chiral expansion. For $N_f=2$, we observe that the prediction to NLO does not converge at the scale of kaon mass. Based on this fact, we extend the analysis to the $N_f=2+1$ case and carry out the extrapolation to the physical mass point using the NNLO formulae.