Chiral Analysis of Quenched Baryon Masses

TL;DR

This paper investigates the chiral structure of baryon masses in quenched QCD, comparing it with full QCD to understand mass splittings, and finds surprisingly little curvature in the quenched case despite including meson-loop effects.

Contribution

It extends previous full QCD analyses to quenched QCD, revealing that meson-loop self-energies have minimal impact on baryon mass curvature in the quenched approximation.

Findings

Quenched QCD shows little curvature in baryon masses despite meson-loop effects.

Replacing quenched meson-loop terms with full QCD results aligns quenched and full QCD baryon masses.

Understanding of baryon mass splitting is improved through this comparison.

Abstract

We extend to quenched QCD an earlier investigation of the chiral structure of the masses of the nucleon and the delta in lattice simulations of full QCD. Even after including the meson-loop self-energies which give rise to the leading and next-to-leading non-analytic behaviour (and hence the most rapid variation in the region of light quark mass), we find surprisingly little curvature in the quenched case. Replacing these meson-loop self-energies by the corresponding terms in full QCD yields a remarkable level of agreement with the results of the full QCD simulations. This comparison leads to a very good understanding of the origins of the mass splitting between these baryons.