Q2dependence of diffractive vector meson electroproduction

Abstract

We give a general formula for the cross section for diffractive vector meson electroproduction, ${\ensuremath{\gamma}}^{*}\stackrel{\ensuremath{\rightarrow}}{p}\mathrm{Vp}.$ We first calculate diffractive $q\overline{q}$ production, and then use parton-hadron duality by projecting out the ${J}^{P}{=1}^{\ensuremath{-}}$ state in the appropriate mass interval. We compare the ${Q}^{2}$ dependence of the cross section for the diffractive production of $\ensuremath{\rho}$ and $J/\ensuremath{\psi}$ mesons with recent DESY HERA data. We include the characteristic ${Q}^{2}$ dependence associated with the use of the skewed gluon distribution. We give predictions for ${\ensuremath{\sigma}}_{L}/{\ensuremath{\sigma}}_{T}$ for both $\ensuremath{\rho}$ and $J/\ensuremath{\psi}$ production.