On baryon-antibaryon coupling to two photons

Abstract

We discuss recent claims that $p\bar{p}\to \gamma \gamma$ may be described by a generalized parton picture. We propose that quark-hadron duality provides a justification for the effective dominance of the "handbag" diagram assumed in recent literature, and that handbag diagrams may dominate phenomena in kinematic regions far more extensive than that might be expected from pQCD alone.

Comments: 11 pages, 2 eps figures, minor modifications made, version to appear on Phys. Lett. B