T. Nakaya

Indications of neutrino oscillation in a 250 km long-baseline experiment.

The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.

Study of late decaying charged particles at future colliders

In models where the gravitino is the lightest supersymmetric particle, the next-to-lightest supersymmetric particle (NLSP) is long-lived. We consider an important charged NLSP candidate, the scalar tau {tau}-tilde. Slow charged NLSPs may be produced at future colliders and they may be stopped in a massive stopper which simultaneously serves as a detector for the NLSP and its decay products. We found the number of events at a 1 kton to O(10) kton detector could be significant enough to study the NLSP decays with lifetime shorter than 10{sup 10}sec at the LHC. The performance of existing 1 kton detectors may be good enough to do such studies at the LHC, if they can be placed close to the ATLAS/CMS detectors. At a future e{sup -}e{sup -} collider, scalar electrons e-tilde{sup -}s are copiously produced. Slow NLSPs may be produced from the e-tilde{sup -} decay. The number of stopped NLSPs at a future linear collider could be large enough to study rare decay modes of the NLSP.

Resolving theta(23) degeneracy by accelerator and reactor neutrino oscillation experiments

If the lepton mixing angle

Search for Charged Current Coherent Pion Production on Carbon in a Few-GeV Neutrino Beam

{\ensuremath{\theta}}_{23}

Development of Multi-Pixel Photon Counters

is not maximal, there arises a problem of ambiguity in determining

Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

{\ensuremath{\theta}}_{23}

Measurement of Inclusive Neutral Current Neutral

due to the existence of two degenerate solutions, one in the first and the other in the second octant. We discuss an experimental strategy for resolving the

\pi^0

{\ensuremath{\theta}}_{23}

Production on Carbon in a Few-GeV Neutrino Beam

octant degeneracy by combining reactor measurement of

Performance of multi-pixel photon counters for the T2K near detectors

{\ensuremath{\theta}}_{13}