Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6 × 10^20 protons on target

Date

2015

Authors

Abe, K.
Adam, J.
Aihara, H.
Akiri, T.
Andreopoulos, C.
Aoki, S.
Ariga, A.
Assylbekov, S.
Autiero, D.
Barbi, M.

Journal Title

Journal ISSN

Volume Title

Publisher

Physical Review D

Abstract

We report on measurements of neutrino oscillation using data from the T2K long-baseline neutrino experiment collected between 2010 and 2013. In an analysis of muon neutrino disappearance alone, we find the following estimates and 68% confidence intervals for the two possible mass hierarchies: normal hierarchy :     sin 2 θ 23 = 0.51 4 + 0.055 − 0.056 and Δ m 2 32 = ( 2.51 ± 0.10 ) × 1 0 − 3     eV 2 / c 4 and inverted hierarchy :     sin 2 θ 23 = 0.511 ± 0.055 and Δ m 2 13 = ( 2.48 ± 0.10 ) × 1 0 − 3     eV 2 / c 4 . The analysis accounts for multinucleon mechanisms in neutrino interactions which were found to introduce negligible bias. We describe our first analyses that combine measurements of muon neutrino disappearance and electron neutrino appearance to estimate four oscillation parameters, | Δ m 2 | , sin 2 θ 23 , sin 2 θ 13 , δ C P , and the mass hierarchy. Frequentist and Bayesian intervals are presented for combinations of these parameters, with and without including recent reactor measurements. At 90% confidence level and including reactor measurements, we exclude the region δ C P = [ 0.15 , 0.83 ] π for normal hierarchy and δ C P = [ − 0.08 , 1.09 ] π for inverted hierarchy. The T2K and reactor data weakly favor the normal hierarchy with a Bayes factor of 2.2. The most probable values and 68% one-dimensional credible intervals for the other oscillation parameters, when reactor data are included, are sin 2 θ 23 = 0.52 8 + 0.055 − 0.038 and | Δ m 2 32 | = ( 2.51 ± 0.11 ) × 1 0 − 3     eV 2 / c 4 .

Description

Keywords

Citation

Abe, K., Adam, J., Aihara, H., Akiri, T., Andreopoulos, C., Karlen, D., … Żmuda, J. (2015). Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6 x 1020. Physical Review D, 91(7), 1-50. https://doi.org/10.1103/PhysRevD.91.072010.