Physics potential of a long-baseline neutrino oscillation experiment using a J-PARC neutrino beam and Hyper-Kamiokande

Hyper-Kamiokande will be a next-generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande.One of the main goals of Hyper-Kamiokande is the study of C P asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams.In this paper, the physics potential of a long-baseline neutrino experiment using the Hyper-Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented.The analysis uses the framework and systematic uncertainties derived from the ongoing T2K experiment.With a total exposure of 7.5 MW ×10 7 s integrated proton beam power (corresponding to 1.56 × 10 22 protons on target with a 30 GeV proton beam) to a 2.5 • off-axis neutrino beam, it is expected that the leptonic C P phase δ C P can be determined to better than 19 degrees for all possible values of δ C P , and C P violation can be established with a