Prompt photon processes in photoproduction at HERA

TL;DR

This paper reports measurements of prompt photon production in photoproduction at HERA, comparing experimental results with theoretical predictions from NLO QCD and Monte Carlo models, enhancing understanding of photon structure.

Contribution

First detailed comparison of prompt photon production data with NLO QCD and Monte Carlo models at HERA energies.

Findings

NLO QCD describes the data well in shape and magnitude.

Measurements cover photon transverse energies 5-10 GeV and jet energies above 5 GeV.

Results improve understanding of photon structure in high-energy photoproduction.

Abstract

We present results for the photoproduction of inclusive prompt photons and for prompt photons accompanied by jets, measured with the ZEUS detector at HERA. Cross sections as a function of pseudorapidity and transverse energy are presented for 5 < E_T^\gamma < 10 GeV, E_T^{jet} > 5 GeV in the centre of mass energy range 120-270 GeV. Comparisons are made with predictions from leading logarithm parton shower Monte Carlos and next-to-leading order QCD calculations using currently available models of the photon structure. NLO QCD calculations describe the shape and magnitude of the measurements reasonably well.