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Exclusive production of pion pairs in gamma* gamma collisions at large Q2

Markus Diehl, Thierry Gousset, Bernard Pire

hep-pharXiv:hep-ph/0003233

Abstract

We perform a QCD analysis of the exclusive production of two mesons in gamma* gamma collisions in the kinematical domain of large photon virtuality Q and small hadronic invariant mass W. This reaction is dominated by a scale invariant mechanism which factorizes into a perturbative subprocess, gamma* gamma --> q qbar or gamma* gamma --> g g, and a generalized two-meson distribution amplitude. We develop in detail the phenomenology of this process at e+ e- colliders. Using a simple model for the two-pion distribution amplitude, based on its general properties, we estimate the cross section for the kinematics accessible at BABAR, BELLE, CLEO and LEP.

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