Photoproduction of a large invariant mass gamma rho pair at small momentum transfer

5 pages, 3 figures, to appear in the proceedings of XXIV International Workshop on Deep-Inelastic Scattering and Related Subject - DIS 2016, 11-15 April 2016, DESY Hamburg, GermanyInternational audienceThe collinear factorization framework allows to describe the exclusive photoproduction of a gamma rho pair in the generalized Bjorken regime in terms of a perturbatively calculable coefficient function and universal generalized parton distributions. The kinematics are defined by a large invariant mass of the gamma rho pair and a small transverse momentum of the final nucleon. We calculate the scattering amplitude at leading order in alpha_s and the differential cross sections for the process where the rho-meson is either longitudinally or transversely polarized, in the kinematics of the near future Jlab experiments. Our estimate of the cross section demonstrates that this process is measurable at JLab 12-GeV