On the convergence of the chiral expansion for the baryon ground-state masses

TL;DR

This paper investigates the convergence of the chiral expansion for baryon masses, demonstrating rapid convergence up to physical strange quark masses and successfully fitting lattice QCD data.

Contribution

It provides explicit expressions up to chiral order five for baryon masses and proposes a reordering of terms to improve convergence properties.

Findings

Chiral expansion converges rapidly up to physical strange quark masses.

Explicit expressions for baryon masses up to chiral order five are derived.

Successful reproduction of lattice QCD baryon masses for ensembles with pion and kaon masses below 600 MeV.

Abstract

We study the chiral expansion of the baryon octet and decuplet masses in the isospin limit. It is illustrated that a chiral expansion of the one-loop contributions is rapidly converging up to quark masses that generously encompasses the mass of the physical strange quark. We express the successive orders in terms of physical meson and baryon masses. In addition, owing to specific correlations amongst the chiral moments, we suggest a reordering of terms that make the convergence properties more manifest. Explicit expressions up to chiral order five are derived for all baryon masses at the one-loop level. The baryon masses obtained do not depend on the renormalization scale. Our scheme is tested against QCD lattice data, where the low-energy parameters are systematically correlated by large-Nc sum rules. A reproduction of the baryon masses from PACS-CS, LHPC, HSC, NPLQCD, QCDSF-UKQCD and ETMC is achieved for ensembles with pion and kaon masses smaller than 600 MeV. Predictions for baryon masses on ensembles from CLS as well as all low-energy constants that enter the baryon masses at N3LO are made.