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

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.