Measurements of the Structure of Diffraction at HERA

TL;DR

This paper presents measurements of diffraction in electron-proton collisions at HERA, showing a universal structure for DIS processes and a factorisation breaking in diffractive photoproduction of dijets.

Contribution

It provides the first detailed comparison of diffraction structures across different processes at HERA, highlighting factorisation breaking in photoproduction.

Findings

DIS processes are consistent with a universal diffraction structure

Factorisation is broken in diffractive photoproduction of dijets by a factor of ~0.5

Results support the universality of diffraction in electron-proton collisions

Abstract

Measurements of diffraction in electron-proton collisions are presented. All measured processes which occur through the exchange of a virtual photon (DIS) are consistent with a universal structure. For the diffractive photoproduction of dijets, factorisation is broken by a global factor ~0.5 with respect to the DIS processes.