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 HyperKamiokande is the study of CP 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��� s integrated proton beam power (corresponding to 1.56 �� 10���� protons on target with a 30 GeV proton beam) to a 2.5-degree off-axis neutrino beam, it is expected that the leptonic CP phase ��CP can be determined to better than 19 degrees for all possible values of ��CP , and CP violation can be established with a statistical significance of more than 3 �� (5 ��) for 76% (58%) of the ��CP parameter space. Using both ��e appearance and ���� disappearance data, the expected 1�� uncertainty of sin���������� is 0.015(0.006) for sin���������� = 0.5(0.45).