Wide-angle pion-Delta(1232) photoproduction

TL;DR

This paper investigates high-energy wide-angle pion-Delta(1232) photoproduction using the handbag mechanism at twist-3 accuracy, relating GPDs to proton GPDs and achieving reasonable experimental agreement.

Contribution

It introduces a twist-3 accurate handbag approach to pion-Delta photoproduction, connecting GPDs to proton GPDs via large-N_C results, with minimal parameters.

Findings

Reasonable agreement with experimental data

Extension of handbag mechanism to pion-Delta production

Use of GPDs related to proton structure

Abstract

High-energy wide-angle photoproduction of pion-Delta final states is investigated within the handbag mechanism to twist-3 accuracy. In this approach the process amplitudes factorize in a hard partonic subprocess and and in form factors which represent 1/x-moments of p-Delta transition generalized parton distributions (GPDs) at zero skewness. The subproces, calculated to twist-3 accuracy, is the same as in pion photoproduction. The p-Delta GPDs are related to the proton-proton GPDs exploiting large-N_C results. The proton-proton GPDs as well as the twist-2 and twist-3 pion distribution amplitudes appearing in the subprocess are taken from other work. Reasonable agreement with experiment is found in this almost parameter-free analysis.