Measurement of inclusive electron cross section in $\gamma \gamma$ collisions at TRISTAN

TL;DR

This paper reports measurements of inclusive electron production in gamma-gamma collisions at TRISTAN, providing insights into charm quark production and photon structure, with results favoring models with high gluon content at small x.

Contribution

First measurement of inclusive electron cross sections in gamma-gamma collisions at TRISTAN, testing photon structure models with NLO corrections and charm-quark mass assumptions.

Findings

Data favor photon models with large gluon content at small x.

Results agree with NLO calculations including charm-quark mass of 1.3 GeV.

Measured cross sections support resolved-photon process contributions.

Abstract

We have studied open charm production in $\gamma \gamma$ collisions with the TOPAZ detector at the TRISTAN $e^{+}e^{-}$ collider. In this study, charm quarks were identified by electrons (and positrons) from semi-leptonic decays of charmed hadrons. The data corresponded to an integrated luminosity of 95.3 pb$^{-1}$ at a center-of-mass energy of 58 GeV. The results are presented as the cross sections of inclusive electron production in $\gamma \gamma$ collisions with an anti-tag condition, as well as the subprocess cross sections, which correspond to resolved-photon processes. The latter were measured by using a sub-sample with remnant jets. A comparison with various theoretical predictions based on direct and resolved-photon processes showed that our data prefer that with relatively large gluon contents in a photon at small $x (x \le 0.1)$, with the next-to-leading order correction, and with a charm-quark mass of 1.3 GeV.