Production of large rapidity gap events in ep interactions at HERA

Abstract

This is a short review of the properties of electron proton interactions characterized by the presence of large rapidity gaps (LRG) in the measured hadronic final state as obtained by the ZEUS Collaboration at the HERA Collider. In the deep inelastic neutral current $ep$ interactions, the factorization properties of the LRG events interpreted as due to the diffractive dissociation of the virtual photon are compatible with expectations from the Regge phenomenology of soft interactions. The measurement of deep inelastic scattering combined with results from photoproduction of high $p_T$ jets are successfully interpreted in terms of a factorizable Pomeron consisting of quarks and with a substantial contribution of a gluonic component. The first hints of a more complicated nature of the Pomeron are observed in the deep inelastic exclusive $\rho^o$ production, where a strong increase of the production cross section with energy is observed relative to the measurements of the NMC Collaboration at lower energy.