M_pi^2 versus m_q: comparing CP-PACS and UKQCD data to Chiral Perturbation Theory

TL;DR

This paper compares lattice QCD data from CP-PACS and UKQCD with Chiral Perturbation Theory predictions for pseudo-Goldstone masses, confirming some theoretical expectations but finding no clear evidence of chiral logs.

Contribution

It provides a comparison of lattice data with chiral theory, supporting the validity of earlier low-energy scale estimates in two-flavor QCD.

Findings

Data consistent with chiral perturbation theory predictions

No clear evidence of chiral logarithms in the data

Supports previous estimates of the low-energy scale b3 in QCD

Abstract

I present a selection of CP-PACS and UKQCD data for the pseudo-Goldstone masses in $N_f=2$ QCD with doubly degenerate quarks. At least the more chiral points should be consistent with Chiral Perturbation Theory for the latter to be useful in an extrapolation to physical masses. I find consistency with the chiral prediction but no striking evidence for chiral logs. Nonetheless, the consistency guarantees that the original estimate, by Gasser and Leutwyler, of the $N_f=2$ QCD low-energy scale $\Lambda_3$ was not entirely wrong.