Precision Electromagnetic Structure of Octet Baryons in the Chiral Regime

TL;DR

This paper calculates the electromagnetic properties of octet baryons using quenched QCD with improved fermion actions, revealing environment sensitivity and confirming theoretical chiral behavior at low quark masses.

Contribution

It introduces efficient quenched QCD simulations with FLIC fermions to study baryon electromagnetic structure, aligning results with quenched chiral perturbation theory.

Findings

Detection of substantial curvature in charge radii and magnetic moments at low quark masses.

Agreement of quenched QCD results with leading non-analytic behavior of quenched chiral perturbation theory.

Observation of environment sensitivity in quark contributions to baryon properties.

Abstract

The electromagnetic properties of the baryon octet are calculated in quenched QCD on a 20^3 x 40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover (FLIC) fermion action. FLIC fermions enable simulations to be performed efficiently at quark masses as low as 300 MeV. By combining FLIC fermions with an improved-conserved vector current, we ensure that discretisation errors occur only at O(a^2) while maintaining current conservation. Magnetic moments and electric and magnetic radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. Our results are compared extensively with the predictions of quenched chiral perturbation theory. We detect substantial curvature and environment sensitivity of the quark contributions to electric charge radii and magnetic moments in the low quark mass region. Furthermore, our quenched QCD simulation results are in accord with the leading non-analytic behaviour of quenched chiral perturbation theory, suggesting that the sum of higher-order terms makes only a small contribution to chiral curvature.