T2K Results and Perspectives

The Tokai-to-Kamioka (T2K) experiment studies neutrino oscillations in a 600 MeV off-axis, high intensity muon-neutrino beam sent 295 km from the Japan Proton Accelerator Complex (J-PARC) to the Super Kamiokande (SK) detector in Kamioka. The primary goals of T2K are the search for the appearance of electron neutrinos at SK resulting from θ13>0 and a precise measurement of θ23 and via the νμ disappearance channel. The T2K collaboration has already published indications of electron neutrino appearance [K. Abe et al., Phys. Rev. Lett. 107, 041801 (2011)] and a first measurement of sin2(θ23) from muon neutrino disappearance [K. Abe et al., Phys. Rev. D 85,(2011) 031103] using the data collected until March 11, 2011. An improved analysis and all the data taken through June 9, 2012 provide now 11 electron neutrino candidates in the far detector, corresponding to 3.2 standard deviations from the θ13=0 hypothesis. This excess is currently the strongest evidence of electron neutrino appearance and it yields, for normal hierarchy and at 68% confidence level.