Single top quark production at LEP200

Abstract A complete tree-level calculation of the reaction e + e − →e + ν e t b (e − ν e t b ) in the electroweak standard theory in the LEP200 energy range is presented. For top quark masses in the range 130 to 190 GeV the cross sections are found to be in the order of 10 −5 to 10 −6 pb. Therefore, the number of single top quark events is expected to be negligible even with an integrated luminosity of L =500 pb −1 . It is further demonstrated that the Weizsacker-Williams approximation approaches the accurate cross section calculations reasonably well.