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Exclusive annihilation p pbar -> gamma gamma in a generalized parton picture

A. Freund·A. V. Radyushkin·A. Schaefer·C. Weiss
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Abstract

Exclusive proton-antiproton annihilation into two photons at large s (~10 GeV^2) and |t|,|u| ~ s can be described by a generalized parton picture analogous to the 'soft mechanism' in wide-angle real Compton scattering. The two photons are emitted in the annihilation of a single fast quark and antiquark. The matrix element describing the transition of the p-pbar system to a q-qbar pair can be related to the timelike proton elastic form factors as well as to the quark/antiquark distributions measured in inclusive deep-inelastic scattering. The reaction could be studied with the proposed 1.5-15 GeV high-luminosity antiproton storage ring (HESR) at GSI.

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A. Freund, A. V. Radyushkin, A. Schaefer, C. Weiss. 2002-08-06. Exclusive annihilation p pbar -> gamma gamma in a generalized parton picture. https://doi.org/10.1103/physrevlett.90.092001

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