T2K reports its first measurements of the parameters governing the disappearance of ν-μ in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic ν-μ beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the ν-μ survival probability is expected to be minimal. Using a data set corresponding to 4.01×1020 protons on target, 34 fully contained μ-like events were observed. The best-fit oscillation parameters are sin2(θ-23)=0.45 and |Δm-322|=2.51×10-3 eV2 with 68% confidence intervals of 0.38-0.64 and 2.26-2.80×10-3 eV2, respectively. These results are in agreement with existing antineutrino parameter measurements and also with the νμ disappearance parameters measured by T2K.
Publication Source (Journal or Book title)
Physical Review Letters
Abe, K., Andreopoulos, C., Antonova, M., Aoki, S., Ariga, A., Assylbekov, S., Autiero, D., Barbi, M., Barker, G., Barr, G., Bartet-Friburg, P., Batkiewicz, M., Bay, F., Berardi, V., Berkman, S., Bhadra, S., Blondel, A., Bolognesi, S., Bordoni, S., Boyd, S., Brailsford, D., Bravar, A., Bronner, C., Buizza Avanzini, M., Calland, R., Cao, S., Caravaca Rodríguez, J., & Cartwright, S. (2016). Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam. Physical Review Letters, 116 (18) https://doi.org/10.1103/PhysRevLett.116.181801