Inclusive Charged Hadron Production in Two-Photon Collisions at LEP

TL;DR

This study measures inclusive charged hadron production in two-photon collisions at LEP, revealing the transition from soft to perturbative QCD processes and highlighting discrepancies with NLO predictions at high transverse momentum.

Contribution

First detailed measurement of charged hadron production in two-photon collisions at LEP energies, comparing data with QCD predictions across a wide p_t range.

Findings

Soft processes dominate at p_t < 1.5 GeV with exponential behavior.

Onset of perturbative QCD observed at higher p_t.

Discrepancy between measured and NLO QCD pi+- production cross sections for p_t > 5 GeV.

Abstract

Inclusive charged hadron production, e+e- -> e+e- h+- X, is studied using 414 pb-1 of data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 202 GeV. Single particle inclusive differential cross sections are measured as a function of the particle transverse momentum, pt, and pseudo-rapidity, eta. For p_t < 1.5 GeV, the data are well described by an exponential, typical of soft hadronic processes. For higher pt, the onset of perturbative QCD processes is observed. The pi+- production cross section for pt > 5 GeV is much higher than the NLO QCD predictions.