Limits on neutral heavy lepton production from Z0 decay

Data taken with the OPAL detector at LEP during a scan of the Z0 resonance were searched for evidence of neutral heavy leptons that decay via mixing. Four different decay modes of the neutral heavy lepton are considered: L0→eW∗, L0→μW∗, L0→τW∗, and L0→vZ∗. No evidence is seen of a neutral heavy lepton signal; branching fraction limits in the range of 10−3–10−4 are set for Z0→L0L0 and for Z0→vL0 (orvL0) relative to Z0→hadrons.