Exclusive photoproduction of a $\gamma\,\rho$ pair with a large   invariant mass
  Exclusive photoproduction of a $\gamma\,\rho$ pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering amplitude is calculated at leading order in $\alpha_s$ and the differential cross sections for the process where the $\rho-$meson is either longitudinally or transversely polarized are estimated in the kinematics of the JLab 12-GeV experiments. 
R. Boussarie, B. Pire, L. Szymanowski, S. Wallon
hep-ph hep-ex nucl-ex nucl-th