Hyperon Electromagnetic Properties in Two-Flavor Chiral Perturbation Theory

TL;DR

This paper uses two-flavor chiral perturbation theory to analyze how hyperon electromagnetic properties depend on pion mass, providing formulas useful for lattice QCD extrapolations and highlighting the theory's effectiveness and limitations.

Contribution

It presents detailed chiral correction formulas for hyperon electromagnetic properties within two-flavor theory, including analysis of virtual kaon effects and pion mass dependence.

Findings

Kaon loop contributions are well described by analytic terms in pion mass squared.

Two-flavor chiral perturbation theory accurately describes certain hyperon properties near physical pion mass.

The approach is useful for extrapolating lattice QCD data at physical strange quark mass.

Abstract

The pion mass dependence of hyperon electromagnetic properties is determined using two-flavor heavy baryon chiral perturbation theory. Specifically we compute chiral corrections to the charge radii, magnetic moments, and magnetic radii of the spin one-half hyperons, as well as the charge radii, magnetic moments, magnetic radii, electric quadrupole moments, and quadrupole radii of the spin three-half hyperons. Results for the nucleon and delta are also included. Efficacy of the two-flavor theory is investigated by analyzing the role played by virtual kaons. For the electromagnetic properties of spin one-half hyperons, kaon loop contributions are shown to be well described by terms analytic in the pion mass squared. Similarly kaon contributions to the magnetic moments of spin three-half hyperons are well described in the two-flavor theory. The remaining electromagnetic properties of spin three-half resonances can be described in two-flavor chiral perturbation theory, however, this description fails just beyond the physical pion mass. For the case of experimentally known hyperon magnetic moments and charge radii, we demonstrate that chiral corrections are under reasonable control, in contrast to the behavior of these observables in the three-flavor chiral expansion. The formulae we derive are ideal for performing the pion mass extrapolation of lattice QCD data obtained at the physical strange quark mass.