NUCLEAR Nuclear Physics B 381 (1992) 87—108 P H Y S I CS B North-Holland _________________ Neutrino masses in supersymmetry with spontaneously broken R-parity J.C. Romão Centro de FIsica da Matéria Condensada, INJC, AL. Prof Garna Pinto, 2-1699 Lisbon Codex, Portugal J.W.F. Valle 2 Instituto de Ficica Corpuscular, CSIC, Departarnent de FIsica Teôrica, Unicersitat de València, 46100 Borjassot, Val?ncia, Spain Received 27 September 1991 (Revised 20 January 1992) Accepted for publication 23 March 1992 The neutrino mass spectrum that arises in supersymmetry models with spontaneously broken R-parity is studied in detail. We analyse the attainable values for rn,, rn, and rn,, 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-/3 decay, the limits from neutrino oscillation searches. etc. For natural choices of the parameters neutrino masses arise in a very striking pattern: while v~ and have masses lying in the adequate range for the explanation of the observed deficit in the solar neutrino flux via the MSW effect, the v~mass is large enough to lead to novel signatures associated with the r-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 ,~i-) as large as 6x iO—~ and single-majoron emission r-decay branching ratios T —~~z +J as large as iO~ corresponding to solar neutrino oscillation parameters in the non-adiabatic branch favoured by present solar neutrino data. The r-neutrino is naturally much heavier than and decays to it via majoron emission, with a lifetime short enough to obey cosmological limits. 1. Introduction Most studies of supersymmetric phenomenology have so far assumed the exact conservation of a discrete symmetry called R-parity. Under this symmetry all particles of the standard model (including the Higgs scalars) are R-even while their Bitnet Centro de Fisica da Matéria Condensada, INIC, Av. Prof. Gama Pinto, 2-1699 Lisbon Codex, Portugal: ROMAO~ PTIFM. 2 Bitnet Instituto de Fisica Corpuscular, CSIC, Departament de FIsica Tehrica, Universitat de Valência. 46100 Burjassot, València, Spain: VALLE~TEVALUN1I - Deenet 16444:: VALLE. 0550-3213/92/$05.00 © 1992 — Elsevier Science Publishers B.V. All rights reserved