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

Abstract

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 $0.5^{\circ }$ to $1.0^{\circ }$ can be observed in Korea. We study physics impacts of putting a 100 kt-level Water \cerenkov detector in Korea during the T2K experimental period. For a combination of the $3^{\circ }$ off-axis beam at SK with baseline length L = 295 km and the $0.5^{\circ }$ off-axis beam in the east coast of Korea at L = 1000 km, we find that the neutrino mass hierarchy (the sign of $m_3^2-m_1^2$) can be resolved and the CP phase of the MNS unitary matrix can be constrained uniquely at 3-$\sigma$ level when \sin^2 2\theta_{\rm rct} $\ge 0.06$.