Strange Baryon Electromagnetic Form Factors and SU(3) Flavor Symmetry Breaking

TL;DR

This study uses lattice QCD calculations to analyze electromagnetic form factors of octet baryons, examining SU(3) flavor symmetry breaking effects and comparing results with experimental data.

Contribution

It provides the first detailed lattice QCD analysis of electromagnetic form factors for multiple octet baryons with SU(3) symmetry breaking effects included.

Findings

Electric and magnetic radii are similar with about 10% discrepancy.

SU(3) symmetry breaking effects are small in the explored pion-mass region.

Predicted charge radii and magnetic moments are within a few standard deviations of experimental values.

Abstract

We study the nucleon, Sigma and cascade octet baryon electromagnetic form factors and the effects of SU(3) flavor symmetry breaking from 2+1-flavor lattice calculations. We find that electric and magnetic radii are similar; the maximum discrepancy is about 10%. In the pion-mass region we explore, both the quark-component and full-baryon moments have small SU(3) symmetry breaking. We extrapolate the charge radii and the magnetic moments using three-flavor heavy-baryon chiral perturbation theory (HBXPT). The systematic errors due to chiral and continuum extrapolations remain significant, giving rise to charge radii for $p$ and $\Sigma^-$ that are 3--4 standard deviations away from the known experimental ones. Within these systematics the predicted $\Sigma^+$ and $\Xi^-$ radii are 0.67(5) and 0.306(15) fm$^2$ respectively. When the next-to-next-to-leading order of HBXPT is included, the extrapolated magnetic moments are less than 3 standard deviations away from PDG values, and the discrepancy is possibly due to remaining chiral and continuum extrapolation errors.