Exclusive photoproduction of a heavy vector meson in QCD

Abstract

The process of exclusive heavy vector meson photoproduction, gamma p -> V p, is studied in the framework of QCD factorization. The mass of the produced meson, V = Upsilon or J/Psi, provides a hard scale for the process. We demonstrate, that in the heavy quark limit and at the one-loop order in perturbation theory, the amplitude factorizes in a convolution of a perturbatively calculable hard-scattering amplitude with the generalized parton densities and the nonrelativistic QCD matrix element <O_1>_V. We evaluate the hard scattering amplitude at one-loop order and compare the data with theoretical predictions using an available model for generalized parton distributions.

Comments: 37 pages, LATEX, 17 figures, the version corrected according to the erratum Eur.Phys.J. C75 (2015) 2, 75 and eqs. (2.21), (3.96), (3.97)