Determination of neutrino mixing parameters after SNO oscillation evidence

An updated analysis of all available neutrino oscillation evidence in solar experiments (SK day and night spectra, global rates from Homestake, SAGE, and GALLEX) including the latest SNO CC and NC data is presented. Assuming that the shape of the SNO CC energy spectrum is undistorted and using the information provided by SNO we obtain, for the fraction of electron neutrinos remaining in the solar beam at energies >~5 MeV, phiCC/phiNC = 0.34-0.04+0.05, which is nominally many standard deviations away from the standard value. The fraction of oscillating neutrinos into active ones is computed to be (PhiNC–PhiCC)/(PhiSSM–PhiCC) = 0.92-0.20+0.39, nearly 5sigma deviations from the pure sterile oscillation case. The data are still compatible with an important fraction of sterile component in the solar beam (up to 20%–30% of the total). In the framework of two active neutrino oscillations we determine individual neutrino mixing parameters and their errors in the region of no spectrum distortion (Delta<1%); we obtain Deltam2 = 4.5-1.4+2.7×10–5 eV2, tan2theta= 0.40-0.08+0.10. These parameters are in agreement with those ones of the best chi2 solution in the LMA region.