Unified treatment of solar and atmospheric neutrino oscillations

Abstract

We present an ansatz for the quark and lepton mass matrices, derivable from SO(1) type GUTs, which accommodates a heavy (> 92 GeV) top quark and permints large mixings in the ν μ → ν τ sector (as suggested by the recent Kamiokande and IMB data on the atmospheric neutrinos). The well known asymptotic relations m b = m τ, m 2 = 1 3 m μ and m d m s = m e m μ all hold to a good approximation. Depending on ν μ → ν τ mixing which can even be maximal, the mixing angle relevant for solar neutrino oscillation lies in the range 7.8 × 10 −3 ⪅ sin 2 2 θ meμ ⪅ 2.1 × 10 −2. For the 71Ga experiment the event rate, normalized against the standard solar model prediction of 132 SNU, is estimated to be between 80 and 20 SNU.