Results and Prospects of the T2K Neutrino Experiment

We report new results from the T2K neutrino oscillation experiment. We observe six electron neutrino events with 1.5 ± 0.3 background events estimated, which indicates the evidence of electron neutrino appearance with non-zero θ₁₃. At 90 % confidence level, the allowed region of θ₁₃ is 0.03(0.04) < sin² 2θ₁₃ < 0.28(0.34) for δ_CP = 0 and a normal (inverted) hierarchy. For the muon neutrino signal, we observe the large disappearance effect due to neutrino oscillations thanks to the narrow band off-axis neutrino beam. We observe 31 muon neutrino events with an expectation of 104 ± 14 events without oscillations, which provides the precise measurements of neutrino oscillation parameters: sin² 2θ₂₃ and . We also introduce the physics potential of the next generation neutrino oscillation experiment for CP violation study with a huge water Čerenkov detector, Hyper-Kamiokande.