The width of the Roper resonance in baryon chiral perturbation theory

TL;DR

This paper computes the width of the Roper resonance using baryon chiral perturbation theory, incorporating dynamical pions, nucleons, and resonances, and finds results consistent with experimental data.

Contribution

It provides a systematic next-to-leading order calculation of the Roper resonance width within baryon chiral perturbation theory including multiple resonances.

Findings

One low-energy constant fixed by empirical decay width.

Calculated Roper decay width aligns with experimental data.

Assumption of coupling constants similar to nucleons yields consistent results.

Abstract

We calculate the width of the Roper resonance at next-to-leading order in a systematic expansion of baryon chiral perturbation theory with pions, nucleons, and the delta and Roper resonances as dynamical degrees of freedom. Three unknown low-energy constants contribute up to the given order. One of them can be fixed by reproducing the empirical value for the width of the Roper decay into a pion and a nucleon. Assuming that the remaining two couplings of the Roper interaction take values equal to those of the nucleon, the result for the width of the Roper decaying into a nucleon and two pions is consistent with the experimental value.