Exploratory study of shrinkage of the diffraction cone for the generalized BFKL pomeron

Abstract

In color dipole gBFKL dynamics, we describe the emerging gBFKL phenomenology of a subasymptotic energy dependence of the diffraction slope and discuss possibilities of testing the gBFKL predictions in exclusive photo- and electroproduction of vector mesons V at HERA. A substantial shrinkage of the diffraction cone γ ∗p → Vp processes from the CERN/FNAL to HERA range of energy W is predicted. This subasymptotic shrinkage is faster than expected from the small slope of pomeron's Regge trajectory α′ p . We point out that the diffraction slope is a scaling function of ( m v 2 + Q 2), which relates production of different vector mesons.