The QCD analysis of hadron-antihadron -> gamma^* gamma in the forward region and related processes

A QCD analysis of the reactions A B -> gamma^* gamma and gamma^* gamma -> A B in the forward region shows that they can be factorized in a way which is quite similar to the frameword developped for deeply virtual Compton scattering. The generalized parton distributions (GPDs) related to this latter process being replaced by new non perturbative hadronic matrix elements, the transition distribution amplitudes (TDAs).