Review of High Energy Diffraction in Real and Virtual Photon Proton scattering at HERA

TL;DR

This paper reviews the experimental results from HERA on high energy diffraction in real and virtual photon-proton scattering, highlighting the energy and virtuality dependence of diffraction processes and their contributions to the total cross section.

Contribution

It provides a comprehensive overview of HERA's diffraction measurements in real and virtual photon-proton interactions up to 2008, including vector meson production and inclusive diffraction.

Findings

Diffraction contributes about 15% at low Q^2, decreasing to 5% at high Q^2.

Results from H1 and ZEUS experiments on vector meson production are summarized.

The energy dependence of diffraction cross sections is analyzed.

Abstract

The electron-proton collider HERA at DESY opened the door for the study of diffraction in real and virtual photon-proton scattering at center-of-mass energies W up to 250 GeV and for large negative mass squared -Q^2 of the virtual photon up to Q^2 = 1600 GeV^2. At W = 220 GeV and Q^2 = 4 GeV^2, diffraction accounts for about 15% of the total virtual photon proton cross section decreasing to ~5% at Q^2 = 200 GeV^2. An overview of the results obtained by the experiments H1 and ZEUS on the production of neutral vectormesons and on inclusive diffraction up to the year 2008 is presented.