Latest Results from T2K

Abstract

The T2K (Tokai to Kamioka) experiment is a long-baseline accelerator neutrino oscillation experiment. Intense muon neutrino and antineutrino beams are produced at the J-PARC accelerator complex situated in Tokai. After 280 metres the beam goes through the set of two near detectors: INGRID and ND280, where the beam parameters before oscillations are measured and neutrino cross-sections are studied. After another 295 km, the distance corresponding to the first oscillation maximum, the neutrino beam passes through the Super-Kamiokande far detector. Comparison of the beam characteristics in the near and far detectors makes it possible to determine the oscillation parameters. Based on muon neutrino disappearance, T2K has delivered the world's leading measurement of the $\theta_{23}$ mixing angle. It has been also the first experiment to observe electron neutrino appearance, with a significance of 7.3$\sigma$. These results made it possible to determine the $\theta_{13}$ mixing angle and to provide the first hint of a non-zero value of the $\delta_{CP}$ phase. The T2K experiment has also delivered several neutrino cross-section measurements at neutrino energies around 1 GeV. Currently, T2K is collecting data with a muon antineutrino beam, for the $\delta_{CP}$ and antineutrino cross-section measurements. A summary of the most recent oscillation measurements, including the new electron antineutrino appearance results, is presented.