Off-diagonal generalized vector dominance in DIS and QCD

We review the generalized vector dominance (GVD) approach to DIS at small values of the scaling variable, x. In particular, we concentrate on a recent formulation of GVD that explicitly incorporates the configuration of the gamma* --> q(q)overbar transition and a QCD-inspired ansatz for the (q(q)overbar)p scattering amplitude. The destructive interference, originally introduced in off-diagonal GVD is traced back to the generic structure of two-gluon exchange. Asymptotically, the transverse photoabsorption cross section behaves as (In Q(2))/Q(2), implying a logarithmic violation of scaling for F-2, while the longitudinal-to-transverse ratio decreases as 1/lnQ(2). We also briefly comment on vector-meson production.