Reconciling cold dark matter with COBE/IRAS plus solar and atmospheric neutrino data Original Research Article

We present a model where an unstable MeV Majorana tau neutrino can naturally reconcile the cold dark matter model (CDM) with cosmological observations of large and small scale density fluctuations and, simultaneously, with data on solar and atmospheric neutrinos. The solar neutrino deficit is explained through long wavelength, so-called just-so oscillations involving conversions of νe into both νμ and a sterile species νs , while atmospheric neutrino data are explained through νμ to νe conversions. Future long baseline neutrino oscillation experiments, as well as some reactor experiments will test this hypothesis. The model is based on the spontaneous violation of a global lepton number symmetry at the weak scale. This symmetry plays a key role in generating the cosmologically required decay of the ντ with lifetime τντ ≈ 102-104 seconds, as well as the masses and oscillations of the three light neutrinos νe, νμ and νs required in order to account for solar and atmospheric neutrino data. It also leads to the invisibly decaying Higgs signature that can be searched at LEP and future particle colliders.