Prompt muons in multiparticle events from e+e- annihilation at petra

Abstract We have observed the production of prompt muons in e + e − annihilation in the centre of mass energy range 33.0 GeV to 35.8 GeV. The rate of such muons with momentum greater than 1.4 GeV was measured to be 0.069 ± 0.024 per multiparticle event. When compared with currently accepted models, this rate is consistent with that expected from charm and bottom decays, but does not support the production also of a top quark of mass less than about 15 GeV.