Abstract
We investigate the implications of the SNO charged-current (CC) and electron scattering (ES) measurements of solar \br neutrino fluxes for neutrino mass and mixing parameters by performing a global and unified $\chi^2$ analysis of the solar neutrino data in the framework of two neutrino mixing. We consider both $\nu_e -\nu_{active}$ and $\nu_e -\nu_{sterile}$ solutions and perform (i) analysis of the total rates data of Cl, Ga, SK and SNO experiments and (ii) global analysis including the total rates data, the recoil electron spectrum data of SK and the CC spectrum observed at SNO. For the $\nu_e-\nu_{active}$ case the inclusion of the SNO results in the analysis of the total rates reduces(enhances) the goodness-of-fit (GOF) of the SMA(LMA) solution. The flat spectrum observed at SK further favours the LMA solution over the SMA solution and no allowed area is obtained in the SMA region at 3$\sigma$ level from the global analysis. For the $\nu_e -\nu_{sterile}$ case, with the inclusion of the SNO results, all the solutions are disfavoured with a probability of more than 99% from the total rates analysis while for the global analysis the GOF of these become much worse.
Highlights
The Sudbury Neutrino Observatory (SNO) has declared its first results [1] on the measurement of solar 8B neutrinos through the CC detection process νe + d → p + p + e−
A comparison of the 8B νe flux measured by the CC reaction (1) with the flux of 8B neutrinos measured at SK signifies the presence of a νμand/or ντ component in the solar neutrino flux at 3.3σ level
The flat recoil electron energy spectrum observed at SK has been responsible in creating a vast change in the allowed oscillation regions and their goodness of fit (GOF) as compared to those obtained from analysis of total rates only [12] -[19]
Summary
The flat recoil electron energy spectrum observed at SK has been responsible in creating a vast change in the allowed oscillation regions and their goodness of fit (GOF) as compared to those obtained from analysis of total rates only [12] -[19]. With the flat electron energy spectrum observed in SK the best-fit in the global analysis of rates and spectrum data shifted to the Large-Mixing-Angle (LMA) region. In this paper we investigate the significance of the SNO results for neutrino mass and mixing parameters by including these in the χ2-analysis of the global solar neutrino data on total rates in Cl, Ga and SK experiments and the SK day-night recoil electron spectrum.
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