Exclusive diffractive photoproduction of dileptons by timelike Compton scattering

We derive the forward photoproduction amplitude for the diffractive gamma p -> l(+)l(-) p reaction in the momentum space, within the formalism of k(perpendicular to)-factorization. Predictions for the gamma p -> l(+)l(-) p reaction are given using unintegrated gluon distribution from the literature. We calculate the total cross section as a function of photon-proton center of mass energy and the invariant mass distribution of the lepton pair. We also discuss whether the production of timelike virtual photons can be approximated by continuing to the spacelike domain q(2) < 0. The present calculation provides an input for future predictions for exclusive hadroproduction in the pp -> pl(+)l(-) p reaction. (C) 2010 Elsevier B.V. All rights reserved.