English

Determination of Neutrino mixing parameters after SNO oscillation evidence

High Energy Physics - Phenomenology 2007-06-22 v3

Abstract

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 \gsim5\gsim 5 MeV: ϕCC/ϕNC=0.340.04+0.05,\phi_{CC}/\phi_{NC}=0.34^{+0.05}_{-0.04}, which is nominally 30σ\sim 30\sigma away from the standard value. The fraction of oscillating neutrinos which into active ones is computed to be: (ΦNCΦCC)/(ΦSSMΦCC)=0.920.20+0.39 (\Phi_{NC}-\Phi_{CC})/(\Phi_{SSM}-\Phi_{CC})=0.92^{+0.39}_{-0.20} nearly 5σ5\sigma deviations from the pure sterile oscillation case. The data is still compatible with an important fraction of sterile component in the solar beam (up to 20% 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 (Δ<Te><1\Delta< T_e> <1%), we obtain Δm2=4.51.4+2.7×105\eV2,tan2θ=0.400.08+0.10.\Delta m^2= 4.5^{+2.7}_{-1.4}\times 10^{-5} \eV^2, \quad \tan^2\theta=0.40^{+0.10}_{-0.08}. This is in agreement with the best chi2chi^2 solution in the LMA region.

Keywords

Cite

@article{arxiv.hep-ph/0205053,
  title  = {Determination of Neutrino mixing parameters after SNO oscillation evidence},
  author = {P. Aliani and V. Antonelli and M. Picariello and R. Ferrari and E. Torrente-Lujan},
  journal= {arXiv preprint arXiv:hep-ph/0205053},
  year   = {2007}
}