PHOTOPRODUCTION OF A πρ PAIR AND TRANSVERSITY GPDs

We demonstrate that the chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed through the exclusive photoproduction process gamma + N -> pi + rho + N', in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversely polarized state. We calculate perturbatively the scattering amplitude at leading order in alpha(s). We build a simple model for the dominant transversity GPD H-T(x,xi,t) based on the concept of double distribution. Counting rates estimates show that the experiment looks feasible with the real photon beam characteristics expected at JLab@12 GeV, in low Q(2) leptoproduction at Jlab@12 GeV and in the COMPASS experiment.