Reconciling Dark Matter, Solar and Atmospheric Neutrinos

Abstract

We present models that can reconcile the solar and atmospheric neutrino data with the existence of a hot dark matter component in the universe. This dark matter is a quasi-Dirac neutrino whose mass $m_{DM}$ arises at the one-loop level. The solar neutrino deficit is explained via nonadiabatic conversions of electron neutrino to a sterile neutrino and the atmospheric neutrino data via maximal muon neutrino to tau neutrino oscillations generated by higher order loop diagrams. For $m_{DM} \sim 30$ eV the radiative neutrino decay can lead to photons that can ionize interstellar hydrogen. In one of the models one can have observable $ν_e$ to $ν_τ$ oscillation rates, with no appreciable muon neutrino oscillations at accelerator experiments. In addition, there can be observable rates for tau number violating processes such as $τ\to 3e$ and $τ\to e + γ$. In the other model one can have sizeable $ν_e$ to $ν_μ$ oscillation rates, as well as sizeable rates for muon number violating processes such as $μ\to e + γ$, $μ\to e + majoron$ and $μ\to 3e$.