The Role of the Roper in Chiral Perturbation Theory

TL;DR

This paper integrates the Roper resonance into heavy-baryon chiral perturbation theory to improve the understanding of nucleon excitations near the delta resonance, showing notable advancements in the $P_{11}$ channel.

Contribution

It introduces the Roper excitation into chiral perturbation theory, enhancing the theoretical description of nucleon resonances at relevant energies.

Findings

Significant improvement in the $P_{11}$ channel.

Better agreement with experimental data.

Enhanced theoretical framework for nucleon excitations.

Abstract

We include the Roper excitation of the nucleon in a version of heavy-baryon chiral perturbation theory recently developed for energies around the delta resonance. We find significant improvement in the $P_{11}$ channel.