An upper limit on additional neutrino mass eigenstate in 2 to 100 eV region from "Troitsk nu-mass" data

TL;DR

This study reanalyzed Troitsk nu-mass data to set an upper limit on the existence of an additional neutrino mass eigenstate in the 2 to 100 eV range, constraining its contribution to less than 1% for masses above 20 eV.

Contribution

It provides the first direct upper limits on additional neutrino mass states in the 2-100 eV range using Troitsk data, extending previous bounds.

Findings

Upper limit of ~1% contribution for neutrino masses above 20 eV.

No evidence found for additional neutrino mass states in the 2-100 eV range.

Constraints improve understanding of neutrino mass spectrum.

Abstract

We performed a search for any sign of an additional neutrino mass state in beta-electron spectrum based on data reanalysis of direct electron antineutrino mass measurements in Tritium beta-decay in the Troitsk nu-mass experiment. The existing data set allows us to search for such a state in the mass range up to 100 eV. The lowest value at a 95% C.L. upper limit for the contribution of a heavy eigenstate into electron neutrino is around or less than 1% for masses above 20 eV.