Abe, K. and Akutsu, R. and Amey, J. and Andreopoulos, C. and Antonova, M. and Aoki, S. and Ariga, A. and Ashida, Y. and Azuma, Y. and Ban, S. and Barbi, M. and Barker, G. J. and Barr, G. and Barry, C. and Batkiewicz, M. and Bench, F. and Berardi, V. and Berkman, S. and Berner, R. M. and Berns, L. and Bhadra, S. and Bienstock, S. and Blondel, A. and Bolognesi, S. and Bourguille, B. and Brailsford, D. and Bravar, A. and Bronner, C. and Avanzini, M. Buizza and Calcutt, J. and Campbell, T. and Cao, S. and Catanesi, M. G. and Cervera, A. and Chappell, A. and Checchia, C. and Cherdack, D. and Chikuma, N. and Christodoulou, G. and Coleman, J. and Collazuol, G. and Coplowe, D. and Dealtry, T. and Finch, A. J. and Knox, A. and Kormos, L. L. and Lawe, M. and Nowak, J. and O'Keeffe, H. M. and Ratoff, P. N. (2018) Search for CP violation in Neutrino and Antineutrino Oscillations by the T2K experiment with $2.2\times10^{21}$ protons on target. Physical review letters, 121 (17). ISSN 1079-7114
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Abstract
The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of $14.7(7.6)\times 10^{20}$ protons on target in neutrino (antineutrino) mode, 89 $\nu_e$ candidates and 7 anti-$\nu_e$ candidates were observed while 67.5 and 9.0 are expected for $\delta_{CP}=0$ and normal mass ordering. The obtained $2\sigma$ confidence interval for the $CP$ violating phase, $\delta_{CP}$, does not include the $CP$-conserving cases ($\delta_{CP}=0,\pi$). The best-fit values of other parameters are $\sin^2\theta_{23} = 0.526^{+0.032}_{-0.036}$ and $\Delta m^2_{32}=2.463\pm0.065\times10^{-3} \mathrm{eV}^2/c^4$.