The Parton Content of the Photon

TL;DR

This paper investigates the photon structure through photon-photon collisions at LEP, measuring the photon structure function, charm and beauty production, and testing perturbative QCD predictions in a previously unexplored low-x region.

Contribution

It provides new measurements of the photon structure function F2g at low x, and reports first observations of beauty production in photon-photon collisions.

Findings

Measured F2g at lowest x values

Extracted total charm quark production cross section

Reported first signs of beauty production

Abstract

The structure of the photon is studied in photon-photon collisions at LEP. New measurements have become available exploring the structure function F2g of the photon to the lowest values of x yet, where the hadronic component of the photon is most important. Inclusive cross sections for charged D* have been measured as a function of their transverse momenta and are used to test the validity of perturbative QCD in NLO in this region. The total charm quark production cross section is extracted. For the first time the inclusive production of D* mesons in deep inelastic electron-photon scattering has been used to extract the charm structure function of the photon. A first sign of beauty production in photon-photon collisions is reported.