Lepton flavor violation and the τ neutrino mass

We point out that, in the left-right symmetric model of weak interactions, if the ντ mass is in the keV to MeV range, there is a correlation between rare decays such as τ→3μ, τ→μee, and the allowed values of the ντ mass. In particular, we point out that a large range of ντ masses are forbidden by the cosmological constraints on mντ and this forbidden range will increase further, as the upper limits on these processes become lower.