T2K (Tokai to Kamioka) is a long baseline neutrino oscillation experiment

A high intensity 30 GeV proton beam at J-PARC is directed towards a graphite target. The charged hadrons produced are focussed by magnetic horns to produce a mostly $\nu_{\mu}$ beam. The near detectors are set at 280 m from the target to monitor and measure the neutrino flux and intensity. The far detector is located 2.5 degrees off-axis at a distance of 295 km from the neutrino production point. This exposes the far detector to a narrow-band neutrino beam peaked at 0.6 GeV which is optimised to give the maximum neutrino oscillation probability and the minimum background to the $\nu_e$ appearance measurement. The current data set analized is $6.57 \times 10^{20}$ protons on target. The T2K experiment has observed 120 $\nu_{\mu}$ events at the far detector although $446 \pm 23$ events are expected without neutrino oscillation. This result leads to $\sin^2 \theta_{23}=0.514_{-0.056}^{+0.055} (0.511 \pm 0.055)$ and $|\Delta m^2_{32}| = (2.51 \pm 0.10) \times 10^{-3} ((2.48 \pm 0.10)\times 10^{-3}$) eV$^{2}$ assuming the normal (inverted) mass hierarchy. For the electron neutrino appearance, we have observed 28 $\nu_{e}$ events and measured $\sin^2 2\theta_{13} = 0.140_{-0.032}^{+0.038} (0.170_{-0.037}^{+0.045})$ assuming the normal (inverted) mass hierarchy, $\sin^2 \theta_{23}=0.5, |\Delta m^2_{32}|=2.4 \times 10^{-3}$ eV $^2$, and $\delta_{CP}=0$. This means 7.3 $\sigma$ significance to $\theta_{13}\neq 0$. In addition to the neutrino oscillation analysis, the neutrino interaction cross section measurements of the inclusive Charged Current, Charged Current quasi-elastic, and neutrino-oxygen neutral-current quasi-elastic channels are reported.