Octet baryon masses and sigma terms from an SU(3) chiral extrapolation

TL;DR

This paper analyzes recent lattice QCD results for octet baryon masses using SU(3) chiral extrapolation, achieving accurate predictions and determining sigma terms, including the strangeness sigma term, with minimal model dependence.

Contribution

It introduces a low order SU(3) chiral expansion method for analyzing lattice QCD data, providing precise baryon mass predictions and sigma term calculations.

Findings

Baryon masses match experimental values with small model dependence.

First lattice-based determination of the strangeness sigma term.

Accurate pion-nucleon sigma commutator obtained.

Abstract

We report an analysis of the impressive new lattice simulation results for octet baryon masses in 2+1-flavor QCD. The analysis is based on a low order expansion about the chiral SU(3) limit in which the symmetry breaking arises from terms linear in the quark masses plus the variation of the Goldstone boson masses in the leading chiral loops. The baryon masses evaluated at the physical light quark masses are in remarkable agreement with the experimental values, with a model dependence considerably smaller than the rather small statistical uncertainty. From the mass formulae one can evaluate the sigma commutators for all octet baryons. This yields an accurate value for the pion-nucleon sigma commutator. It also yields the first determination of the strangeness sigma term based on 2+1-flavor lattice QCD and, in general, the sigma commutators provide a resolution to the difficult issue of fine-tuning the strange quark mass.