Abstract

We revisit the sensitivity study of the Tokai-to-Kamioka-and-Korea (T2KK) and Tokai-to-Kamioka-and-Oki (T2KO) proposals where a water check{mathrm{C}}erenkov detector with the 100 kton fiducial volume is placed in Korea (L = 1000 km) and Oki island (L = 653 km) in Japan, respectively, in addition to the Super-Kamiokande for determination of the neutrino mass hierarchy and leptonic CP phase (delta _{scriptscriptstyle mathrm{CP}}). We systematically study the running ratio of the nu _mu and {bar{nu }}_mu focusing beams with dedicated background estimation for the nu _e appearance and nu _mu disappearance signals, especially improving treatment of the neutral-current pi ^0 backgrounds. Using a nu _mu –{bar{nu }}_mu beam ratio between 3:2 and 2.5:2.5 (in units of 10^{21}POT with the proton energy of 40 GeV), the mass-hierarchy determination with the median sensitivity of 3–5 sigma by the T2KK and 1–4 sigma by the T2KO experiment are expected when sin ^2 theta _{23} = 0.5, depending on the mass-hierarchy pattern and CP phase. These sensitivities are enhanced (reduced) by 30–40% in Delta chi ^2 when sin ^2 theta _{23} = 0.6, (0.4). The CP phase is measured with the uncertainty of 20^circ –50^circ by the T2KK and T2KO using the nu _mu –{bar{nu }}_mu focusing beam ratio between 3.5:1.5 and 1.5:3.5. These findings indicate that inclusion of the {bar{nu }}_mu focusing beam improves the sensitivities of the T2KK and T2KO experiments to both the mass-hierarchy determination and the leptonic CP phase measurement simultaneously with the preferred beam ratio being between 3:2–2.5:2.5 ({times } 10^{21}POT).

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call