Pomeron physics in diffractive deep inelastic scattering at large 1/x

Abstract

I review recent progress in the perturbative QCD approach to pomeron physics in deep inelastic scattering (DIS) at large1/x.(refs.1–4). I discuss the crucial role the color transparency plays in a diffractioe DIS, and how it can be quantified in terms of the wave function (WF) of (partonic) hadronic fluctuations of photons and universal, flavour independent, qqpair interaction cross section. Different DIS processes probe this universal cross section at different sizes. The emerging WF formalism greatly simplifies the involved calculations. I present quantitative predictions for the nuclear shadowing and the diffraction dissociation (DD) rate in DIS, and the valence and sea quark distributions in a QCD Pomeron. I point out a dramatic difference of sea densities in a nucleon as probed by muons and neutrinos and flavour dependence of the pomeron couplings in DD and conclude that perturbative QCD pomeron does not factorize. I emphasize a numerical importance of shadowing in deuterium for tests of the Gottfried sum rule.