Eur. Phys. J. A (2005) 26: 89-98
https://doi.org/10.1140/epja/i2005-10153-8

Original Article

The process p¯↦γπwithin the handbag approach

¹ Fachbereich Physik, Universität Wuppertal, D-42097, Wuppertal, Germany
² Institut für Theoretische Physik, Universität Regensburg, D-93040, Regensburg, Germany

Received: 14 June 2005
Accepted: 8 September 2005
Published online: 26 October 2005

Abstract

We analyse the exclusive channel p¯↦γπ⁰, assuming handbag dominance. The soft parts are parametrized in terms of CGLN amplitudes for the q¯↦γπ⁰ transition and form factors for the p¯↦q¯ ones; the latter represent moments of Generalized Distribution Amplitudes. We present a combined fit to Fermilab data from E760 taking simultaneously into account information from other exclusive reactions, especially from p¯↦γγ data. Overall a nicely consistent picture emerges, such that one can hope, that our theoretical analysis will be reliable also for the kinematics of GSI/FAIR, which, hopefully, will provide much more precise and complete data. Consequently, data from this facility should improve our knowledge both on the proton-antiproton distribution amplitudes and the pion production mechanism.