Deeply Virtual Compton Scattering and Prompt Photon production at HERA

TL;DR

This paper reports recent measurements of Deeply Virtual Compton Scattering and prompt photon production at HERA, comparing experimental results with theoretical models including NLO QCD and GPDs, and exploring cross section dependencies.

Contribution

It provides new DVCS cross section measurements, including the first report of dependence on the momentum transfer squared, and compares prompt photon production data with NLO QCD predictions.

Findings

DVCS cross sections measured for specific kinematic ranges

First report of cross section dependence on momentum transfer t

Prompt photon production results agree with NLO QCD predictions

Abstract

Recent results on the Deeply Virtual Compton Scattering (DVCS) and prompt photon productions from H1 and ZEUS experiments on the $ep$ collider HERA are presented. A new DVCS cross section measurements of the H1 Collaboration, for photon virtualities $Q^2>4$ GeV$^2$ and photon-proton c.m.s. energy $30<W<140$ GeV, are discussed and compared to NLO QCD calculations encoding Generalized Parton Distributions (GPDs) and to Colour Dipole model predictions. For the first time the cross section dependence is reported on the momentum transfer squared at the proton vertex, $t$. Prompt photon production in deep inelastic scattering and photoproduction are presented both in the inclusive case and in the presence of a jet. The results are compared to NLO QCD predictions.