Search for Single Top Quark Production at LEP2

TL;DR

This paper reports a search for single top quark production via flavor-changing neutral currents at LEP2, using extensive data, but finds no evidence and sets upper limits on production rates and anomalous couplings.

Contribution

First search for single top quark production via FCNC at LEP2, establishing upper limits on cross-sections and anomalous couplings with comprehensive data analysis.

Findings

No evidence for FCNC single top production.

Set upper limits on production cross-section.

Derived constraints on anomalous couplings kappa_gamma and kappa_Z.

Abstract

A search for single top quark production via flavour changing neutral currents (FCNC) was performed with data collected by the OPAL detector at the e+e- collider LEP. Approximately 600 pb-1 of data collected at sqrt(s) = 189 - 209 GeV were used to search for the FCNC process e+ e- -> tc(u) -> bWc(u). This analysis is sensitive to the leptonic and the hadronic decay modes of the W boson. No evidence for a FCNC process is observed. Upper limits at the 95% confidence level on the single top production cross-section as a function of the centre-of-mass energy are derived. Limits on the anomalous coupling parameters kappa_gamma and kappa_Z are determined from these results.