Solving the neutrino parameter degeneracy by measuring the T2K off-axis beam in Korea

The T2K neutrino oscillation experiment will start in 2009. In this experiment the center of the neutrino beam from J-PARC at Tokai village will go through underground beneath Super-Kamiokande, reach the sea level east of Korean shore, and an off-axis beam at 0.5° to 1.0° can be observed in Korea. We study physics impacts of putting a 100 kt-level water Čerenkov detector in Korea during the T2K experimental period. For a combination of the 3° off-axis beam at SK with baseline length L=295km and the 0.5° off-axis beam in the east coast of Korea at L=1000km, we find that the neutrino mass hierarchy (the sign of m32−m12) can be resolved and the CP phase of the MNS unitary matrix can be constrained uniquely at 3σ level when sin22θrct≳0.06.