Considerations Suggest an Inverted Neutrino Mass Hierarchy ?

A ST R O -P H -9 50 20 81 Do Experiments and Astrophysical Considerations Suggest an Inverted Neutrino Mass Hierarchy? George M. Fuller Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 Joel R. Primack Department of Physics, University of California, Santa Cruz, Santa Cruz, CA 95064 and Yong-Zhong Qian Institute for Nuclear Theory, NK-12, University of Washington, Seattle, WA 98195 ABSTRACT The recent results from the Los Alamos neutrino oscillation experiment, together with assumptions of neutrino oscillation solutions for the solar and atmospheric neutrino de cit problems, may place powerful constraints on any putative scheme for neutrino masses and mixings. Assuming the validity of these experiments and assumptions, we argue that a nearly unique spectrum of neutrino masses emerges as a t, if two additional astrophysical arguments are adopted: (1) the sum of the light neutrino masses is 5 eV, as large scale structure simulations with mixed cold plus hot dark matter seem to suggest; and (2) rprocess nucleosynthesis originates in neutrino-heated ejecta from Type II supernovae. In this t, the masses of the neutrinos must satisfy m e m s 2:7 eV (where e is split from a sterile species, s, by 10 6 eV) and m m 1:1 eV (where these species are split by 10 2 eV). We discuss alternative neutrino mass spectra that are allowed if we decline to adopt certain experiments or astrophysical models. PACS numbers: 14.60.Pq, 95.30.Cq, 97.10.Cv, 97.60.Bw, 98.65.Dx