LMA MSW solution of the solar neutrino problem and first KamLAND results

The first KamLAND results are in a very good agreement with the predictions made on the basis of the solar neutrino data and the LMA realization of the MSW mechanism. We perform a combined analysis of the KamLAND (rate, spectrum) and the solar neutrino data with a free boron neutrino flux fB. The best fit values of neutrino parameters are ∆m2 = 7.3 · 10−5 eV2, tan2 θ = 0.41 and fB = 1.05 with the 1σ intervals: ∆m2 = (6.2−8.4) ·10−5 eV2, tan2 θ = 0.33−0.54. We find the 3σ upper bounds: ∆m2 < 2.8 ·10−4 eV2 and tan2 θ < 0.84, and the lower bound ∆m2 > 4 ·10−5 eV2. At 99% C.L. the KamLAND spectral result splits the LMA region into two parts with the preferred one at ∆m2 < 10−4 eV2. The higher ∆m2 region is accepted at about 2σ level. We show that effects of non-zero 13-mixing, sin θ13 ≤ 0.04, are small leading to slight improvement of the fit in higher ∆m2 region. In the best fit point we predict for SNO: CC/NC = 0.33 −0.03 and A SNO DN = 2.8 ± 0.8% (68% C.L.), and ASNO DN < 9% at the 3σ level. Further improvements in the determination of the parameters are discussed and implications of the solar neutrino and KamLAND results are considered.