Deep inelastic scattering, QCD, and generalized vector dominance

Abstract. We provide a formulation of generalized vector dominance (GVD) for low–x deep-inelastic scattering that explicitly incorporates the ${\gamma}^{\ast} \to q{\bar q}$ transition and a QCD-inspired ansatz for the $(q{\bar q})p$ forward-scattering amplitude. The destructive interference originally introduced in off-diagonal GVD is recovered in the present formulation and traced back to the generic structure of two-gluon-exchange as incorporated into the notion of colour transparency. Asymptotically, the transverse photoabsorption cross section behaves as $(\ln Q^2)/Q^2$, implying a logarithmic violation of scaling for $F_2$, while the longitudinal-to-transverse ratio decreases as $1/\ln Q^2$.