Pion photoproduction in a dynamical coupled-channel model

TL;DR

This paper develops a gauge-invariant dynamical coupled-channel model for pion photoproduction, successfully describing experimental cross sections and asymmetries up to 1.65 GeV using a comprehensive hadronic interaction framework.

Contribution

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

Findings

Accurately reproduces differential cross sections up to 1.65 GeV

Successfully describes photon spin asymmetries

Maintains gauge invariance in the photoproduction amplitude

Abstract

Pion photoproduction reactions are investigated in a dynamical coupled-channel approach based on the Juelich pi-N model, which presently includes the hadronic pi-N and eta-N stable channels as well as the pi-Delta, sigma-N and rho-N effective channels. This model 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 pi0 p and gamma n to pi- p are in good agreement with the experimental data.