Search for Heavy Isosinglet Neutrino in e+e- Annihilation at LEP

TL;DR

This paper reports a search for heavy isosinglet neutrinos in electron-positron collisions at LEP energies, finding no evidence and setting upper limits on their mixing with light neutrinos.

Contribution

It presents the first search for first-generation heavy isosinglet neutrinos at LEP energies, providing new constraints on their properties.

Findings

No evidence for heavy neutrinos in the 80-205 GeV range.

Upper limits established on the mixing parameter between heavy and light neutrinos.

Data collected at energies between 130 and 208 GeV used for analysis.

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 N_e --> eW is investigated and no evidence is found for a heavy neutrino, N_e, in a mass range between 80 GeV and 205 GeV. Upper limits on the mixing parameter between the heavy and light neutrino are derived.