Global analysis of solar neutrino and KamLAND data

A global analysis of the data from all the solar neutrino experiments combined with the recent KamLAND data is presented. A formula frequently used in the literature gives survival probability for three active solar neutrino flavours in terms of a suitably modified two-flavour survival probability. Corrections to this formula, which depend on θ₁₃ and δm²₃₁, are calculated. For the mass scale suggested by the atmospheric neutrino experiments the contributions of δm²₃₁ to these corrections are found to be negligible. The role of θ₁₃ in solar neutrino physics is elaborated. For electron neutrino oscillations into another active flavour, we find best fit values of tan² θ₁₂ ∼ 0.46, tan² θ₁₃ ∼ 0 and δm²₂₁ ∼ 7.1 × 10⁻⁵ eV². It is found that the combined solar neutrino and KamLAND data provide the limit cos⁴ θ₁₃ > 0.8 at the 90% confidence level.