Search for lepton flavour number violating Z0- decays

A search for lepton flavour number violating Z⁰ decays in the channels Z ⁰ → μτ, Z ⁰ → eτ, Z ⁰ → eμ, using the DELPHI detector with data collected during the 1991–94 LEP runs, is described. No signal was found. Upper limits at 95% confidence level for the respective branching fractions of 1.2 × 10^?5, 2.2 × 10^?5, and 0.25 × 10^?5, were obtained.