XXth International Conference on Neutrino Physics and Astrophysics

Poster Abstract


Measuring the CP-Violating Phase by a Long Baseline Neutrino Experiment with Hyper-Kamiokande

We study the sensitivity of a long-base-line (LBL) experiment with neutrino beams from the High Intensity Proton Accelerator (HIPA) that delivers 10^22 POT per year and a proposed 1 Mt water-Cherenkov detector, Hyper-Kamiokande (HK), to the CP phase (delta_mns) of the three-flavor lepton mixing matrix. We examine a combination of the nu_mu narrow-band beam (NBB) at two different energies, vev{p_pi} = 2, 3 GeV, and the anti-nu_mu NBB at vev{p_pi} = 2 GeV. By allocating one year each for the two nu_mu beams and four years for the anti-nu_mu beam, we can efficiently measure the nu_mu -> nu_e and anti-nu_mu -> anti-nu_e transition probabilities, as well as the nu_mu and anti-nu_mu survival probabilities. CP violation in the lepton sector can be established at 3 sigma level if the MSW large-mixing-angle scenario of the solar-neutrino deficit is realized, delta_mns ~ 90^o or 270^o, and if 2|Ue3|^2 (1-|Ue3|^2) = sin^2(2 theta_chooz) > 0.01. The delta_mns is more difficult to constrain by this experiment if there is little CP violation, delta_mns ~ 0^o or 180^o; it is constrained at 1 sigma (2 sigma) level if sin^2(2theta_chooz) >~ 0.01 (>~ 0.06).

Based on a paper in preparation.

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