Diffractive parton density functions

Abstract

We discuss the perturbative QCD description of diffractive deep-inelastic scattering, and extract diffractive parton distributions from recent HERA data. The asymptotic collinear factorisation theorem has important modifications in the sub-asymptotic HERA regime. In addition to the usual resolved Pomeron contribution, the direct interaction of the Pomeron must also be accounted for. The diffractive parton distributions are shown to satisfy an inhomogeneous evolution equation, analogous to the parton distributions of the photon.

Comments: 10 pages, 6 figures. To appear in the proceedings of the Ringberg Workshop on "New Trends in HERA Physics 2005", Ringberg Castle, Tegernsee, Germany, 2-7 October 2005