Y. Takeuchi

Abstract: We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor ${\ensuremath{ u}}_{\ensuremath{\mu}}\ensuremath{\leftrightarrow}{\ensuremath{ u}}_{\ensuremath{\tau}}$ oscillations with ${sin}^{2}2\ensuremath{\theta}g0.82$ and $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}l\ensuremath{\Delta}{m}^{2}l6\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}3}\mathrm{eV}{}^{2}$ at 90% confidence level.

TL;DR: The T2K experiment observes indications of ν (μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target, and under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance.

TL;DR: Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented and the recoil electron energy spectrum is consistent with no spectral distortion.

TL;DR: The T2K experiment as discussed by the authors is a long-baseline neutrino oscillation experiment whose main goal is to measure the last unknown lepton sector mixing angle by observing its appearance in a particle beam generated by the J-PARC accelerator.

TL;DR: Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons as discussed by the authors, which collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency.