SU(2) chiral perturbation theory low-energy constants from staggered 2+1 flavor simulations

TL;DR

This paper determines low-energy constants of SU(2) chiral perturbation theory using lattice QCD simulations with 2+1 flavors, analyzing pion properties across various masses and lattice scales to test chPT's extrapolation reliability.

Contribution

It provides new lattice-based measurements of l_3 and l_4 constants and assesses SU(2) chPT's effectiveness for higher pion mass extrapolations.

Findings

Measured pion mass and decay constant on multiple ensembles.

Extracted NLO low-energy constants l_3 and l_4.

Tested SU(2) chPT's reliability for extrapolation from higher masses.

Abstract

We measure the pion mass and decay constant on ensembles generated by the Wuppertal-Budapest Collaboration, and extract the NLO low-energy constants l_3 and l_4 of SU(2) chiral perturbation theory. The data are generated in 2+1 flavor simulations with Symanzik glue and 2-fold stout-smeared staggered fermions, with pion masses varying from 135 MeV to 400 MeV, lattice scales between 0.7 GeV and 2.0 GeV, and m_s kept at its physical value. Furthermore, by excluding the lightest mass points, we are able to test the reliability of SU(2) chPT as a tool to extrapolate towards the physical point from higher pion masses.