A Sterile Neutrino Needed for Heavy-Element Nucleosynthesis

Abstract

A neutrino mass-mixing scheme which successfully avoids the "alpha effect," allowing r-process nucleosynthesis in the neutrino-heated ejecta of supernovae, quite independently requires the same parameters as the scheme which best fits all current indications for neutrino mass. The significance for particle physics is this independent evidence for (1) at least one light sterile neutrino, nu_s; (2) a near maximally-mixed nu_mu-nu_tau doublet split from a lower mass nu_mu-nu_s doublet; (3) nu_mu-nu_e mixing >~ 10^-4; and (4) a splitting between the doublets (measured by the nu_mu-nu_e mass difference) >~ 1 eV^2, favoring the upper part of the LSND range. If correct, it is tantalizing that neutrinos with tiny masses which mix with sterile species have profound effects on massive objects and the creation of the heaviest elements.