Paper detail

Neutrino mass parameters from Kamland, SNO and other solar evidence

An updated analysis of all available neutrino oscillation evidence in Reactor (Kamland, first 145 days of data) and Solar experiments (SK day and night spectra, global rates from Homestake, SAGE and GALLEX) including the $SNO CC$ and $NC$ data is presented. In the framework of two active neutrino oscillations we determine the allowed regions in neutrino parameter space, we obtain, from the Kamland spectral shape and global signal, the following antineutrino best solution parameters, $ Δm^2_{kl}= 7.7\times 10^{-5} \eV^2, \tan^2θ_{kl}= 0.98.$ The overall effect of the measured observed ratio $R\sim 0.6$ is that the LMA region remains the only one which is still favored. Combining Kamland and Solar data and assuming CPT invariance, i.e. the same mass matrix for neutrino and antineutrinos, we obtain the following antineutrino best solution parameters (LMAI solution), $ Δm^2= 7.1\times 10^{-5} \eV^2,\tan^2θ= 0.47.$ A second solution (LMAII) appears for values $ Δm^2= 1.5\times 10^{-4} \eV^2, \tan^2θ= 0.48.$ We determine additionally individual neutrino mixing parameters and their errors from fits to marginal likelihood distributions, the values are compatible with previous results. In both methods, $χ^2$ minimization and marginal likelihood, the combined analysis of solar and Kamland data concludes that maximal mixing is not favored at the $\sim 3σ$ level at least.