Photoproduction of the $\pi N$ pair on nuclei and isobar configurations

TL;DR

This paper develops a model for high-momentum transfer pion-nucleon pair photoproduction on nuclei, incorporating delta-isobar components into the nuclear wavefunction, and provides numerical estimates for specific reactions near the Delta resonance.

Contribution

It introduces an extended impulse approximation model including delta-isobar components for describing nuclear photoproduction of pion-nucleon pairs.

Findings

Numerical estimates for differential cross sections of specific reactions.

Analysis of direct and exchange mechanisms in nuclear photoproduction.

Application of the model near the Delta(1232) resonance region.

Abstract

A model of $\pi N$ pair photoproduction on nuclei at high momentum transfer is presented. The $A(\gamma,\pi N)B$ reaction amplitude is obtained by means of an extended impulse approximation, according to which the nuclear wavefunction includes delta-isobar components in addition to nucleon components. A one-particle transition operator is defined in terms of the two-body $\gamma N\to\pi N$ and $\gamma \Delta\to\pi N$ photoproduction amplitudes. Direct and exchange mechanisms of the nuclear photoproduction reaction are studied, and numerical estimates are made and presented of $^{12}{\rm C}(\gamma,\pi^- p){^{11}{\rm C}}$ and $^{12}{\rm C}(\gamma,\pi^+ p){^{11}{\rm Be}}$ differential cross sections at photon incident energies in the $\Delta(1232)$ resonance region.