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.

生成讲解博客的中文版本

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