Search for single top quark production at LEP2

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−1of data collected at 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 κγand κZare determined from these results.