High momentum particle and jet production in photon-photon collisions

TL;DR

This paper reviews measurements of jet and particle production in photon-photon collisions at LEP2, highlighting agreements and discrepancies between experimental data and NLO perturbative QCD predictions across different experiments.

Contribution

It provides a comparative analysis of experimental results from OPAL, DELPHI, and L3, revealing inconsistencies in high transverse momentum regions and discussing their implications.

Findings

OPAL and DELPHI agree with NLO QCD for di-jet cross sections.

L3 finds significant disagreement with NLO QCD at high jet momenta.

DELPHI's recent measurements do not confirm L3's observed discrepancies.

Abstract

Jet and particle production have been studied in collisions of quasi-real photons collected during the LEP2 program. OPAL and DELPHI report good agreement of NLO perturbative QCD with the measured differential di-jet cross sections, which reach a mean transverse energy of the di-jet system of 25 GeV. L3, on the other hand, finds drastic disagreement of the same calculation with single jet production for transverse jet momenta larger than about 25 GeV. L3 observes similar disagreement between data and NLO QCD in their measurements of charged and neutral particle production at high transverse momenta of the particles. A recent measurement performed by DELPHI of the same quantities does not confirm this observation.