Prompt Photons in Photoproduction at HERA

TL;DR

This paper reports measurements of prompt photon production in electron-proton collisions at HERA, comparing experimental cross sections with QCD predictions to test theoretical models in photoproduction.

Contribution

First measurement of prompt photon cross sections in photoproduction at HERA with detailed comparisons to QCD models.

Findings

Measured cross sections for prompt photons and associated jets.

Observed correlations between photons and jets.

Data generally consistent with QCD predictions.

Abstract

The production of prompt photons is measured in the photoproduction regime of electron-proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340 pb^-1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the range 6 < Et < 15 GeV and -1.0 < eta < 2.4, respectively. Cross sections for events with an additional jet are measured as a function of the transverse energy and pseudorapidity of the jet, and as a function of the fractional momenta x_gamma and x_p carried by the partons entering the hard scattering process. The correlation between the photon and the jet is also studied. The results are compared with QCD predictions based on the collinear and on the k_T factorisation approaches.