Real and virtual photon structure from dijet events

TL;DR

This paper presents measurements of dijet production in ep collisions, revealing new insights into the gluon density of real photons and the partonic structure of virtual photons, challenging existing theoretical models.

Contribution

It provides the first measurements of the partonic density of virtual photons and compares dijet cross sections with NLO QCD calculations to explore photon structure.

Findings

Gluon density of real photons at low x measured

Partonic density of virtual photons studied for the first time

Comparison with NLO QCD highlights complexities in virtual photon structure

Abstract

Jet production in $ep$ collisions is sensitive to the partonic structure of photon. The latest measurements of dijet production from the H1 experiment provide new results of the gluon density of real photons at low $x$ and, for the first time, on the partonic density of virtual photons. Properties of the photon remnant were measured as a function of the hard scale defined by the $p_T$ of the jets. The comparison of dijet cross sections with the NLO QCD calculation shows the non-triviality of the concept of virtual photon structure.