Solar neutrinos: Global analysis with day and night spectra from SNO

We perform global analysis of the solar neutrino data including the day and night spectra of events at SNO. In the context of two active neutrino mixing, the best fit of the data is provided by the large-mixing angle (LMA) Mikheyev-Smirnov-Wolfenstein solution with Δm²=6.15×10^-5eV²,tan²θ=0.41,fB=1.05, where fB is the boron neutrino flux in units of the corresponding flux in the standard solar model (SSM). At the 3σ level we find the following upper bounds: tan²θ<0.84 and Δm²<3.6×10^-4eV². From a 1σ interval we expect the day-night asymmetries of the charged current and electron scattering events to be ADNCC=3.9_-2.9+3.6% and ADNES=2.1_-1.4+2.1%. The only other solution which appears at the 3σ level is the VAC solution with Δm²=4.5×10^-10eV², tan²θ=2.1, and fB=0.75. The best fit point in the low probability, low mass region, with Δm²=0.93×10^-7eV² and tan²θ=0.64, is accepted at 99.95% (3.5σ) C.L. The least χ² point from the small mixing angle solution region, with Δm²=4.6×10^-6eV² and tan²θ=5×10^-4, could be accepted at the 5.5σ level only. In the three neutrino context the influence of θ₁₃ is studied. We find that with an increase of θ₁₃ the LMA best fit point shifts to a larger Δm², the mixing angle is practically unchanged, and the quality of the fit becomes worse. The fits of LOW and SMA slightly improve. Predictions for the KamLAND experiment (total rates, spectrum distortion) have been calculated.