Baryon masses and \sigma-terms in SU(3) BChPT x 1/Nc

TL;DR

This paper combines chiral and 1/Nc expansions to study baryon masses and sigma-terms, addressing the sigma-term puzzle and incorporating lattice QCD data for more accurate results.

Contribution

It introduces a combined effective theory approach for baryon properties that clarifies the sigma-term puzzle and includes lattice QCD data for improved estimates.

Findings

Nucleon sigma-terms have a well-behaved low energy expansion.

A specific mass combination is affected by large higher order corrections.

Lattice QCD data yields sigma_piN ≈ 69 MeV with large uncertainty.

Abstract

Baryon masses and nucleon \sigma-terms are studied with the effective theory that combines the chiral and 1/Nc expansions for three flavors. In particular the connection between the deviation of the Gell-Mann-Okubo relation and the \sigma-term corresponding to the scalar density associated with the hypercharge is emphasized. The latter is at lowest order related to a mass combination whose low value has given rise to a \sigma- term puzzle. It is shown that while the nucleon \sigma-terms have a well behaved low energy expansion, that mass combination is affected by large higher order corrections non-analytic in quark masses. Adding to the analysis lattice QCD baryon masses, it is found that {\sigma}{\pi}N=69(10) MeV and {\sigma}s has natural magnitude within its relative large uncertainty.