The Delta(1232) Resonance in Chiral Effective Field Theory

TL;DR

This paper develops an extension of baryon chiral perturbation theory to include the $
232$ resonance, enabling better modeling of pion production near the resonance region.

Contribution

It introduces a modified power counting scheme in chiral effective field theory to incorporate the $
232$ resonance explicitly.

Findings

Extended chiral perturbation theory accurately describes pion production in the $
232$ resonance region.

Provides a framework for including light resonances in baryon chiral perturbation theory.

Reviews recent applications to pion production reactions.

Abstract

I discuss the problem of formulating the baryon chiral perturbation theory ($\chi$PT) in the presence of a light resonance, such as the $\Delta(1232)$, the lightest nucleon resonance. It is shown how to extend the power counting of $\chi$PT to correctly account for the resonant contributions. Recent applications of the resulting chiral effective-field theory to the description of pion production reactions in $\Delta$-resonance region are briefly reviewed.