Exclusive photoproduction of J/ψ and Upsilon at one-loop accuracy in collinear factorisation with GPD evolution and high-energy resummation

Abstract

We report on the first complete study at one-loop accuracy of J/ψ and Upsilon exclusive photoproduction off protons in Collinear Factorisation (CF) including GPD evolution.  We present our solution to the NLO perturbative instability of the cross section at high photon-proton centre of mass energies: we have matched high-energy factorisation (HEF) which resums higher-order QCD corrections enhanced by a logarithm of the parton energies in the Doubly-Logarithmic Approximation (DLA) to CF. This is particularly relevant at high photon-proton centre of mass energies UPCs at the LHC.