Bounds on neutrino masses from particle physics and cosmology

We study the constraints imposed on the masses of nu/sub e/, nu/sub μ/ and nu/sub tau/ on the basis of direct experimental bounds, cosmological bounds, theoretical calculations of neutrino decay rates, experimental bounds on related decays of charged leptons and the structure of neutrino mass matrices in the ''see-saw'' mechanism. We consider standard model amplitudes as well as contributions from all ''beyond standard'' models. Assuming a simple ''reasonable'' form of the see-saw mechanism, we derive the bounds: m(nu/sub tau/) ≤ 65 eV, m(nu/sub μ/) ≤ 4 eV, m(nu/sub e/) ≤ 0.02 eV, M(W/sub R/) ≥ 50 PeV