NEUTRINO OSCILLATIONS AND MIXED DARK-MATTER

There is increasing evidence that neutrinos, massless in the Standard Model, have mass. If the deficit of solar neutrinos, the ratio of nu(mu)/nu(e) from atmospheric neutrinos being less than expected, and the need for some hot dark matter are all manifestations of neutrino mass, then there are only two viable patterns for these masses: (A) the three active neutrinos, nu(e), nu(mu), and nu(tau), are all similar to 1.6 eV, or (B) the nu(e) and a sterile neutrino, nu(s), are both light, and the nu(mu) and nu(tau), are each similar to 2.4 eV. Recent preliminary results from the LSND experiment, looking for nu(mu) --> nu(e) and ($) over bar nu(mu) --> ($) over bar nu(e), favor (B), since these indications of oscillations are consistent with a nu(mu) mass of similar to 2.4 eV. Furthermore, if scheme (B) is used in a model in which 20% of the dark matter is ''hot'' (along with similar to 7% baryonic and similar to 73% cold dark matter), then the structure of the universe on all scales is fit remarkably well, better than any other model.