Neutrino masses in supersymmetry with spontaneously broken R-parity

The neutrino mass spectrum that arises in supersymmetry models with spontaneously broken R-parity is studied in detail. We analyse the attainable values for mνe, mνμ and mντ, once all observational constraints have been incorporated, including both those that arise from collider experiments such as LEP, as well as weak interaction constraints, such as the non-observation of neutrinoless double-β decay, the limits from neutrino oscillation searches, etc. For natural choices of the parameters neutrino masses arise in a very striking pattern: while νe and νμ have masses lying in the adequate range for the explanation of the observed deficit in the solar neutrino flux via the MSW effect, the ντ mass is large enough to lead to novel signatures associated with the τ-lepton that could be seen both at LEP as well as at a tau factory. These provide an additional tool to probe the parameters characterizing the solar neutrino conversions in conventional accelerator experiments. The related processes include the single-chargino Z-decay branching ratio BR(Z → χ Τ) as large as ∝ 6 x 10-5 and single-majoron emission τ-decay branching ratios τ → μ + J as large as ∝ 10-4 corresponding to solar neutrino oscillation parameters in the non-adiabatic branch favoured by present solar neutrino data. The τ-neutrino is naturally much heavier than νμ and decays to it via majoron emission, with a lifetime short enough to obey cosmological limits. (orig.)