Probing chiral-even and chiral-odd leading twist quark generalized parton distributions through the exclusive photoproduction of a γρ pair

We extend our studies of a new class of 2 -> 3 exclusive processes using the collinear factorization framework by considering the exclusive photoproduction of a gamma rho pair, in the kinematics where the pair has a large invariant mass, and the outgoing rho meson has a sufficiently large transverse momentum to not resonate with the nucleon. We cover the whole kinematical range from medium energies in fixed-target experiments to very large energies of colliders, by considering the experimental conditions of JLab 12-GeV, COMPASS, and future EIC and LHC (in ultra-peripheral collisions) cases. One of the main interests in studying the present process is that it provides access to both chiral-even and chiral-odd generalized parton distributions, depending on the polarization of the outgoing rho meson, both at leading twist. Our analysis covers both neutral and charged rho mesons. We find that the orders of magnitude of the obtained cross sections are sufficiently large for a dedicated experimental analysis to be performed, especially at JLab, for both longitudinally and transversely polarized rho. Furthermore, we compute the linear photon beam polarization asymmetry which is sizable for a longitudinally polarized meson. These predictions are obtained for both the asymptotic distribution amplitude (DA) and the holographic DA.

Automated summary

We extend our studies of a new class of 2 -> 3 exclusive processes by considering the exclusive photoproduction of a gamma rho pair. Our analysis covers the whole kinematical range from medium energies in fixed-target experiments to very large energies of colliders. We find that the obtained cross sections are sufficiently large for a dedicated experimental analysis to be performed, especially at JLab.