Inclusive Production of Charged Hadrons and K_s Mesons in Photon-Photon Collisions

TL;DR

This paper measures the production of charged hadrons and K_s mesons in photon-photon collisions at LEP, comparing experimental data with theoretical models and providing evidence for hard photon interactions beyond purely hadronic ones.

Contribution

It presents the first detailed measurements of hadron and meson production in photon-photon collisions at LEP energies, comparing results with NLO QCD and Monte Carlo simulations.

Findings

Differential cross-sections match NLO QCD predictions.

Evidence of hard photon interactions beyond hadronic models.

Distributions measured over a broad hadronic mass range.

Abstract

The production of charged hadrons and K_s mesons in the collisions of quasi-real photons has been measured using the OPAL detector at LEP. The data were taken at e+e- centre-of-mass energies of 161 and 172 GeV. The differential cross-sections as a function of the transverse momentum and the pseudorapidity of the charged hadrons and K_s mesons have been compared to the leading order Monte Carlo simulations of PHOJET and PYTHIA and to perturbative next-to-leading order (NLO) QCD calculations. The distributions have been measured in the range 10-125 GeV of the hadronic invariant mass W. By comparing the transverse momentum distribution of charged hadrons measured in gamma-gamma interactions with gamma-proton and meson-proton data we find evidence for hard photon interactions in addition to the purely hadronic photon interactions.