Search for Heavy Isosinglet Neutrinos in e$^+$e$^-$ Annihilation at 130$<\sqrt{s}<$189 GeV

TL;DR

This paper reports a search for heavy isosinglet neutrinos at LEP energies, setting upper limits on their mixing with light neutrinos for masses between 80 and 185 GeV.

Contribution

First search for heavy isosinglet neutrinos in e+e- collisions at LEP energies, providing new constraints on their mixing parameters.

Findings

No evidence of heavy neutrinos was observed.

Upper limits on mixing parameters were established.

Mass range explored was 80 to 185 GeV.

Abstract

A search for heavy neutrinos that are isosinglets under the standard $SU(2)_L$ gauge group is made at center-of-mass energies 130 $< \sqrt{s} <$ 189 GeV with the L3 detector at LEP. Such heavy neutrinos are expected in many extensions of the Standard Model. The search is performed for the first generation heavy singlet neutrino, $\mathrm{N}_e$, through the decay mode $\mathrm{N}_e \to \mathrm{e} + \mathrm{W}$. We set upper limits on the mixing parameter between the heavy and light neutrino for the heavy neutrino mass range from 80 GeV to 185 GeV.