COSMOLOGICAL SIGNATURES OF SUPERSYMMETRY WITH SPONTANEOUSLY BROKEN R-PARITY

We discuss mechanisms of spontaneous R parity breaking provided by nonzero sneutrino vacuum expectation values (VEVs) <nu-R approximately> = upsilon-R, <nu-L approximately> = upsilon-L with (upsilon-L << upsilon-R). With the standard SU (2) x U (1) gauge structure this is associated with the existence of a majoron. The majoron, J, is mostly an isosinglet sneutrino (nu-R approximately) which does not contribute to Z0 decay. The assumption that the lightest supersymmetric particle - neutralino - is responsible for the observed dark matter in the Universe implies that R parity violation is extremely weak. Lower limits on neutralino lifetime tau-chi are imposed by the decays chi --> nu-L + q + qBAR and chi --> nu-L + e- + e- which produce diffuse X-ray radiation and high energy positrons in our Galaxy. The main neutralino decay channel chi --> nu + J can produce a detectable monoenergetic neutrino flux, with the number of neutrino events up to approximately 10(3) events per 1 kiloton per year in underground detectors. The gamma-ray line produces by the decay chi --> nu + gamma-decay can be detectable in the case of large m-chi and upsilon-R.