Search for heavy isosinglet neutrino in e+e− annihilation at LEP

Abstract

We report on a search for the first generation heavy neutrino that is an isosinglet under the standard SU(2)L gauge group. The data collected with the L3 detector at center-of-mass energies between 130 GeV and 208 GeV are used. The decay channel Ne →eW is investigated and no evidence is found for a heavy neutrino, Ne, in a mass range between 80 GeV and 205 GeV. Upper limits on the mixing parameter between the heavy and light neutrino are derived.