CONSISTENT NEUTRINO MASSES FROM COSMOLOGY AND SOLAR PHYSICS

THE solar neutrino problem and cosmological dark matter can both be accounted for by non-zero neutrino masses1-5 that are broadly compatible with the so-called 'see-saw' relation, which comes from a simple theoretical model6 for the neutrino masses and according to which the mass of each neutrino type is proportional to the square of the mass of the associated quark. Recently both the solar and the cosmological estimates of neutrino masses have been considerably improved. New solar neutrino data7 lead to a more precise constraint8,9 on the masses of the electron and either the muon or tau neutrinos if the dearth of detected solar neutrinos is ascribed to resonantly enhanced mixing of neutrino types within the Sun (the MSW effect10,11). In addition, if galactic H I ionization is a consequence of decaying tau neutrinos that constitute dark matter, a more precise estimate of the tau neutrino mass follows12. Here I point out that these more accurate estimates still conform to the see-saw relation, a result which, unless it is a chance agreement, ties together three unproven hypotheses: the see-saw mechanism, the MSW effect and the decaying neutrino hypothesis. © 1990 Nature Publishing Group.