Global Analysis with SNO: Toward the Solution of the Solar Neutrino Problem

We perform a global analysis of the latest solar neutrino data including the recently announced SNO result on the CC-event rate. This result further favors the LMA solution of the solar neutrino problem. The best fit values of parameters we find are: $\Delta m^2 = (4.8 - 5.5) 10^{-5}$ eV^2, $\tan^2 \theta = 0.36 - 0.38$, f_B = 1.08 - 1.10, and f_{hep} = 1 - 3. With respect to this best fit point the LOW solution is accepted at 90 % C.L.. The Vacuum oscillation solution with $\Delta m^2 = 1.4 10^{-10}$ eV$^2$, gives good fit of the data (accepted at 90 % C.L.) provided that the boron neutrino flux is substantially smaller than in the SSM ($f_B \sim 0.5$). The SMA solution is accepted only at $3 \sigma$ level. We find that vacuum oscillations to sterile neutrino, VAC(sterile) solution, with $f_B \sim 0.5$ also gives good fit of the data. All other sterile neutrino solutions are strongly disfavored. We check the quality of the fit by constructing the pull-off diagrams for the global solutions. Predictions for the day-night asymmetry and spectrum distortion in SNO are calculated. In the best fit points of the global solutions we find: $A_{DN}^{CC} \approx (7 - 8)%$ for LMA, $\sim (0.8 - 2.5) %$ for LOW, and $(1 - 2) %$ for SMA. It will be difficult to see the distortion of the spectrum expected for LMA (turn up of the spectrum at low energies) as well as LOW solutions. However, future SNO spectrum data can significantly affect the VAC and SMA solutions