Photoproduction of a pi rhoT pair with a large invariant mass and transversity generalized parton distribution

Understand

The chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed experimentally 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 transversally 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.
• We estimate the unpolarized differential cross section for this process in the kinematics of the Jlab and COMPASS experiments.