Diffractive photoproduction of dijets in ep collisions at HERA

TL;DR

This paper reports measurements of diffractive dijet photoproduction in ep collisions at HERA, comparing experimental data with perturbative QCD predictions to explore the structure of the proton and the nature of diffraction.

Contribution

First measurement of diffractive dijet photoproduction at HERA with detailed comparison to QCD models and diffractive parton distributions.

Findings

Measured differential cross sections in specified kinematic range.

Found agreement/discrepancies with perturbative QCD calculations.

Provided insights into the diffractive structure of the proton.

Abstract

Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb-1. The measurements were made in the kinematic range Q^2 < 1 GeV^2, 0.20 < y < 0.85 and x_pom < 0.025, where Q^2 is the photon virtuality, y is the inelasticity and x_pom is the fraction of the proton momentum taken by the diffractive exchange. The two jets with the highest transverse energy, E_T^jet, were required to satisfy E_T^jet > 7.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5 < eta^jet < 1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton.