Narrow Results

If sterile neutrinos have a neutral coupling to standard model fermions, matter effect resonant transitions to sterile neutrinos and excess neutral-current events could manifest at long baseline experiments. Assuming a single sterile neutrino with a neutral coupling to fermionic matter, we re-examine bounds on sterile neutrino production at long baselines from the MINOS result P_{νμ →νs} < 0.22 (90% CL). We demonstrate that sterile neutrinos with a neutral vector coupling to fermionic matter could evade the MINOS limit, allowing a higher fraction of active to sterile neutrino conversion at long baselines. Scanning the parameter space of sterile neutrino matter effect fits of the LSND and MiniBooNe data, we show that in the case of a vector singlet coupling of sterile neutrinos to matter, some favored parametrizations of these fits would create neutral-current event excesses above standard model predictions at long baseline experiments (e.g. MINOS and OPERA).

The Hyper-Kamiokande is a next generation large water Cherenkov detector proposed to be built in Kamioka, Japan. It aims at precision studies of neutrino oscillation parameters, including the CP violation phase δ_CP , using neutrinos from the J-PARC accelerator as well as atmospheric neutrinos. The detector also serves as a general purpose observatory, expanding the existing sensitivities by an order of magnitude in the searches for nucleon decays, solar and galactic WIMPs, and supernova neutrinos.