Electroproduction of vector mesons - factorization of end-point contributions

Abstract

The end-point contributions in the quark longitudinal momentum fraction of the virtual photon (${\gamma }^{\ast }$) to vector meson ($V$) impact factor to the diffractive electroproduction amplitude can be factorized in terms of a generalized parton evolution of the target parton distribution. The result is used to model the helicity amplitudes ${\gamma }^{\ast }p\to Vp$ in terms of small $x$ generalized parton distributions.

Comments: 24 pages LaTex, 4 eps-figures