Solar neutrinos: the SNO salt phase results and physics of conversion

Abstract

We have performed analysis of the solar neutrino data including results from the SNO salt phase as well as the combined analysis of the solar and the KamLAND results. The best-fit values of neutrino parameters are Δ m 2=7.1×10 −5 eV 2, tan 2 θ=0.40 with the boron flux f B=1.04. New SNO results strongly disfavor maximal mixing and the h-LMA region (Δ m 2>10 −4 eV 2) which is accepted now at the 3 σ level. We find the 3 σ upper bounds: Δ m 2<1.7×10 −4 eV 2 and tan 2 θ<0.64, and the lower bound Δ m 2>4.8×10 −5 eV 2. Non-zero 13-mixing does not change these results significantly. The present data determine quantitatively the physical picture of the solar neutrino conversion. At high energies relevant for SNO and Super-Kamiokande the deviation of the effective survival probability from the non-oscillatory value is about 10–14%. The oscillation effect contribution to this difference is about 10% and the earth regeneration about 3–4%. At low energies ( E<1 MeV) the matter corrections to vacuum oscillation effect are below 5%. The predictions for the forthcoming measurements are given which include the spectral distortion and CC/NC ratio at SNO, the day–night asymmetry, the KamLAND spectrum and rate.