The structure of the Troika: Proton, Photon and Pomeron, as seen at HERA

Abstract

HERA, the electron-proton collider, enables to probe the proton with a high resolving power due to the deep inelastic scattering reactions at high $Q^2$ values. In the low $Q^2$ region, one can study the properties of the photon. The large fraction of diffractive events found both in the low and high $Q^2$ region allows the study of the Pomeron. A review of what we have learned from HERA so far about the structure of these three objects is presented.

52 pages, including 52 figures. Talk presented at the XXI International Workshop on the Fundamental Problems of High Energy Physics and Field Theory, 23-25 June 1998, Protvino, Russia