Effect of Leptonic CP Phase in ν μ → ν μ Oscillations

In the case of large 1-3 mixing angle as sin 2θ13 ≥ 0.03, we investigate the possibility for measuring the leptonic CP phase by using only νμ → νμ oscillations independently of νμ → νe oscillations. As the result, we find that the best setup to measure the CP phase without strongly depending on the uncertainties of the other parameters is around the energy E = 0.43GeV and the baseline length L = 5000km. In this region, the CP phase effect remains even after averaging over the neutrino energy. We also find that there is a CP sensitivity even in the short baseline length L ≤ 1000km if ∆m31 is determined with an uncertainty of about 0.1%. In the T2KK experiment, we explore the possibility for measuring the CP phase by using a baseline from Tokai to Kamioka after determining ∆m31 at the baseline to Korea. As the result, we find that some information of the CP phase can be obtained from the measurements.