Dijet photoproduction of massless charm jets at next-to-leading order of QCD

TL;DR

This paper presents next-to-leading order QCD calculations for charm dijet photoproduction, comparing predictions with ZEUS data, and highlighting the sensitivity to the charm content in the photon.

Contribution

It provides the first NLO QCD predictions for charm dijet photoproduction in the zero-mass scheme and compares them with experimental data, emphasizing the role of photon charm content.

Findings

Predictions agree well with ZEUS data at high momentum fractions.

Low momentum fraction predictions are sensitive to photon charm content.

Data favor models with substantial charm quark density in the photon.

Abstract

We compute the charm dijet photoproduction cross section at next-to-leading order of QCD in the zero-mass variable flavour number scheme, i.e. with active charm quarks in the proton and photon. The results are compared to recent measurements from the ZEUS experiment at HERA. The predictions for various distributions agree well with the data, in particular for large momentum fractions of the the partons in the photon, where direct photon processes dominate. At low momentum fractions, the predictions are quite sensitive to the charm content in the photon. The experimental data are shown to favour parameterizations with a substantial charm quark density such as the one proposed by Cornet et al.