Measurement of Muon Neutrino Disappearance with the T2K Experiment

Abstract

We describe the measurement of muon neutrino disappearance due toneutrino oscillation using the Tokai-2-Kamiokande (T2K) experiment's Run 1-4 (6.57×1020 POT)data set. We analyze the data using the conventionalPontecorvo-Maki-Nakagawa-Sakata (PMNS) mixingmatrix for the three Standard Model neutrinos. The output of theanalysis is a measurement of the parameters sin2θ23, Δm232 for the normal hierarchy and sin2θ23, Δm213 forthe inverted hierarchy. The best-fit oscillationparameters for the normal hierarchy are found to be(sin2θ23, Δm232) = ( 0.514, 2.51×10-3 eV2/c4}). The 90% 1D confidence interval -- determined for both parametersusing the Feldman-Cousins procedure -- is for the normal hierarchy0.428 < sin2θ23 < 0.598 and2.34×10-3 eV2/c4 < Δm232 < 2.68\times10^{-3} eV2/c4. For the inverted hierarchy, the best-fit oscillation parameters are(sin2θ23, Δm213) = (0.511, 2.48×10-3 eV2/c4. The 90\% 1D Feldman-Cousins confidence intervals for the inverted hierarchy are 2.31×10-3 eV2/c4 < \Delta m^2_{13} < 2.64×10-3 eV2/c4.