Spin asymmetry for the 16O(gamma,pi- p) reaction in the Delta(1232) region within an effective Lagrangian approach

TL;DR

This paper presents a relativistic model for photon-induced pion production on oxygen, accurately predicting spin asymmetries in the Delta(1232) region without requiring medium modifications, aligning well with experimental data.

Contribution

The study introduces a fully relativistic approach incorporating spin-3/2 resonances to model spin asymmetries in photonuclear reactions, improving agreement with experimental data.

Findings

Model accurately predicts spin asymmetry data for oxygen

No significant medium modifications needed for Delta(1232)

Relativistic treatment improves upon previous models

Abstract

The spin asymmetry of the photon in the exclusive A(gamma,pi N)A-1 reaction is computed employing a recently developed fully relativistic model based on elementary pion production amplitudes that include a consistent treatment of the spin-3/2 nucleon resonances. We compare the results of this model to the only available data on Oxygen [Phys. Rev. C 61 (2000) 054609] and find that, contrary to other models, the predicted spin asymmetry compares well to the available experimental data in the Delta(1232) region. Our results indicate that no major medium modifications in the Delta(1232) properties are needed in order to describe the measured spin asymmetries.