Anomalous e+e- and μ+μ- events produced in e+e- annihilation

The authors have observed events of the form e++e- → e++e- and e++e- → μ++μ- in which there are no other detected particles and there is substantial missing energy; and which cannot be explained by conventional electromagnetic interactions. It is shown that these events can be explained as the decay products from the pair production, e+ + e- → tau+ + tau-, of a new charged lepton, tau+-, of mass approximately 1800 MeV/c2. Some properties of these events are presented. In particular, this production cross section is inconsistent with the tau being an electron-related paralepton. (Auth.)