Dynamical coupled-channels model study of pion photoproduction

TL;DR

This paper develops a dynamical coupled-channels model for pion photoproduction off nucleons, achieving gauge invariance and accurately reproducing experimental cross sections and asymmetries up to 1.65 GeV.

Contribution

It introduces a gauge-invariant dynamical coupled-channels approach based on the Juelich pi-N model for pion photoproduction, extending previous pi-N scattering models.

Findings

Good agreement with experimental differential cross sections.

Accurate reproduction of photon spin asymmetries.

Model successfully describes reactions up to 1.65 GeV.

Abstract

The photoproduction of pion off nucleon is investigated within a dynamical coupled-channels approach based on the Juelich pi-N model, which has been quite successful in the description of pi-N to pi-N scattering for center-of-mass energies up to 1.9 GeV. The full pion photoproduction amplitude is constructed to satisfy the generalized Ward-Takahashi identity and hence, it is fully gauge invariant. The calculated differential cross sections and photon spin asymmetries up to 1.65 GeV center-of-mass energy for the reactions gamma p to pi^+ n, gamma p to pi^0 p and gamma n to pi^- p are in good agreement with the experimental data.