First result of the muon antineutrino disappearance by T2K

概要

The T2K experiment observed electron-neutrino appearance from a muon-neutrino beam in 2012. This observation enables T2K to explore the CP violation in the lepton sector by comparing the electron-neutrino appearance and electron-antineutrino appearance. Since 2013, T2K has been accumulating data with an muon antineutrino beam. Only a small portion of the produced muon neutrino oscillates to electron neutrino and the majority oscillates to tau neutrino and　disappears because the energy is below the tau-production threshold. The CPT theorem imposes that the disappearance rate must be same for muon neutrino and muon antineutrino. So the comparison between neutrino and antineutrino is a good test of the CPT theorem or to probe for new non-standard interaction of neutrino with matter. In this seminar, we will present T2K's first result of the muon-antineutrino disappearance measurement and compare it with those obtained with the neutrino beam.