Sterile neutrinos in tau lepton decays

Abstract

We study possible contributions of heavy sterile neutrinos $ν_h$ to the decays $τ^-\to e^{\pm}(μ^{\pm})π^{\mp}π^-$. From the experimental upper bounds on their rates we derive new constraints on the $ν_h-ν_τ$ mixing in the mass region $140.5{MeV}\leq m_{ν_h}\leq 1637$ MeV. We discuss cosmological and astrophysical status of $ν_h$ in this mass region and compare our constraints with those recently derived by the NOMAD collaboration.