Real and Virtual Photon Structure at HERA

TL;DR

This paper investigates the structure of real and virtual photons through dijet production in ep collisions at HERA, comparing experimental data with QCD predictions to enhance understanding of photon parton distributions.

Contribution

It provides new measurements of dijet cross sections as functions of photon momentum fraction and virtuality, testing current photon structure models against experimental data.

Findings

Measured differential dijet cross sections as functions of photon momentum fraction.

Analyzed the dependence of cross sections on photon virtuality and jet transverse energy.

Compared data with QCD calculations based on existing photon parton distribution functions.

Abstract

The structure of real and virtual photons has been studied in ep collisions at HERA using dijet production. Measurements of differential dijet cross sections as function of the fraction of photon's momentum invested in the dijet system are presented. The dependence of the cross sections on the virtuality of the photon and mean transverse energy squared of the two leading jets has been investigated. QCD calculations based on current parametrizations of the real and virtual photon parton distribution functions have been compared to the data.