Search for lepton flavor violation in e+ e- collisions at s**(1/2) = 189-GeV - 209-GeV

We search for lepton flavour violating events (e μ , e τ and μτ ) that could be directly produced in e + e − annihilations, using the full available data sample collected with the OPAL detector at centre-of-mass energies between 189 GeV and 209 GeV. In general, the Standard Model expectations describe the data well for all the channels and at each s . A single e μ event is observed where according to our Monte Carlo simulations only 0.019 events are expected from Standard Model processes. We obtain the first limits on the cross-sections σ (e + e − →e μ , e τ and μτ ) as a function of s at LEP2 energies.