Evidence for heavy leptons from anomalous $μ$e production in $e^+$$e^−$ annihilation

Abstract

Events of the type e + e − →μ ± +e ∓ + “nothing” have been observed in the magnetic detector PLUTO at the storage ring DORIS at DESY. The data support the hypothesis of the pair production of heavy leptons, and allow to determine decay parameters. Decay rates into muons and electrons are equal within error, and argue for a new lepton number of the heavy lepton