Electromagnetic properties of baryons

TL;DR

This paper investigates the electromagnetic properties of baryons, especially the nucleon and Delta(1232), using covariant baryon chiral perturbation theory to understand their pion mass dependence and finite volume effects.

Contribution

It provides a complete one-loop calculation up to order p^4/Delta, analyzing the chiral behavior and defining resonance magnetic moments under specific conditions.

Findings

Magnetic moments of resonances depend on mass and magnetic field relations.

Pion mass dependence shows singularities and cusps for Delta(1232).

Finite volume effects influence the iso-vector anomalous magnetic moment.

Abstract

We discuss the chiral behavior of nucleon and Delta(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p^3 and p^4/Delta with Delta as the Delta(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined through the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the Delta(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present results for finite volume effects on the iso-vector anomalous magnetic moment.