Low energy constants from the chirally improved Dirac operator D_CI

TL;DR

This paper presents a quenched lattice QCD calculation of low energy constants using the chirally improved Dirac operator, providing ab-initio estimates for parameters like f_pi, f_K, and quark masses.

Contribution

It introduces a method to compute low energy constants from lattice QCD with the chirally improved Dirac operator, achieving consistent results across different lattice setups.

Findings

f_pi = 96(2) MeV

f_K = 105(2) MeV

m = 4.1(2.4) MeV

Abstract

The leading order low energy parameters like the pion decay constant or the quark condensate are well-known from "classical" low energy theorems and experiments. It is a challenge, however, to find these parameters based exclusively on an ab-initio QCD calculation. We discuss results of a quenched lattice calculation of low energy constants using the chirally improved Dirac operator. Several lattice sizes at different lattice spacings are studied, using pseudoscalar and axial vector correlators. We find consistent results for f_\pi = 96(2) MeV, f_K = 105(2) MeV, \Sigma = -(286(4) MeV)^3, the average light quark mass m = 4.1(2.4) MeV and m_s = 101(8) MeV.