Solar neutrino results in Super-Kamiokande-III

Abstract

The results of the third phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first and second phase results. With improved detector calibrations, a full detector simulation, and improved analysis methods, the systematic uncertainty on the total neutrino flux is estimated to be $\ifmmode\pm\else\textpm\fi{}2.1%$, which is about two thirds of the systematic uncertainty for the first phase of Super-Kamiokande. The observed $^{8}\mathrm{B}$ solar flux in the 5.0 to 20 MeV total electron energy region is $2.32\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{sys})\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{sec}}^{\ensuremath{-}1}$ under the assumption of pure electron-flavor content, in agreement with previous measurements. A combined oscillation analysis is carried out using SK-I, II, and III data, and the results are also combined with the results of other solar neutrino experiments. The best-fit oscillation parameters are obtained to be ${sin}^{2}{\ensuremath{\theta}}_{12}={0.30}_{\ensuremath{-}0.01}^{+0.02}({tan}^{2}{\ensuremath{\theta}}_{12}={0.42}_{\ensuremath{-}0.02}^{+0.04})$ and $\ensuremath{\Delta}{m}_{21}^{2}={6.2}_{\ensuremath{-}1.9}^{+1.1}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{eV}}^{2}$. Combined with KamLAND results, the best-fit oscillation parameters are found to be ${sin}^{2}{\ensuremath{\theta}}_{12}=0.31\ifmmode\pm\else\textpm\fi{}0.01({tan}^{2}{\ensuremath{\theta}}_{12}=0.44\ifmmode\pm\else\textpm\fi{}0.03)$ and $\ensuremath{\Delta}{m}_{21}^{2}=7.6\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{eV}}^{2}$. The $^{8}\mathrm{B}$ neutrino flux obtained from global solar neutrino experiments is $5.3\ifmmode\pm\else\textpm\fi{}0.2(\mathrm{stat}+\mathrm{sys})\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, while the $^{8}\mathrm{B}$ flux becomes $5.1\ifmmode\pm\else\textpm\fi{}0.1(\mathrm{stat}+\mathrm{sys})\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ by adding KamLAND results. In a three-flavor analysis combining all solar neutrino experiments, the upper limit of ${sin}^{2}{\ensuremath{\theta}}_{13}$ is 0.060 at 95% C.L.. After combination with KamLAND results, the upper limit of ${sin}^{2}{\ensuremath{\theta}}_{13}$ is found to be 0.059 at 95% C.L.