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arXiv · 1807.07891

Search for CP violation in Neutrino and Antineutrino Oscillations by the T2K experiment with $2.2\times10^{21}$ protons on target

K. Abe·R. Akutsu·A. Ali·J. Amey·C. Andreopoulos·L. Anthony·M. Antonova·S. Aoki·A. Ariga·Y. Ashida·Y. Azuma·S. Ban·M. Barbi·G. J. Barker·G. Barr·C. Barry·M. Batkiewicz·F. Bench·V. Berardi·S. Berkman·R. M. Berner·L. Berns·S. Bhadra·S. Bienstock·A. Blondel·S. Bolognesi·B. Bourguille·S. B. Boyd·D. Brailsford·A. Bravar·C. Bronner·M. Buizza Avanzini·J. Calcutt·T. Campbell·S. Cao·S. L. Cartwright·M. G. Catanesi·A. Cervera·A. Chappell·C. Checchia·D. Cherdack·N. Chikuma·G. Christodoulou·J. Coleman·G. Collazuol·D. Coplowe·A. Cudd·A. Dabrowska·G. De Rosa·T. Dealtry·P. F. Denner·S. R. Dennis·C. Densham·F. Di Lodovico·N. Dokania·S. Dolan·O. Drapier·K. E. Duffy·J. Dumarchez·P. Dunne·S. Emery-Schrenk·A. Ereditato·P. Fernandez·T. Feusels·A. J. Finch·G. A. Fiorentini·G. Fiorillo·C. Francois·M. Friend·Y. Fujii·R. Fujita·D. Fukuda·Y. Fukuda·K. Gameil·C. Giganti·F. Gizzarelli·T. Golan·M. Gonin·D. R. Hadley·L. Haegel·J. T. Haigh·P. Hamacher-Baumann·D. Hansen·J. Harada·M. Hartz·T. Hasegawa·N. C. Hastings·T. Hayashino·Y. Hayato·A. Hiramoto·M. Hogan·J. Holeczek·F. Hosomi·A. K. Ichikawa·M. Ikeda·J. Imber·T. Inoue·R. A. Intonti·T. Ishida·T. Ishii
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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 $\Delta m^2_{32}=2.463^{+0.071}_{-0.070}\times10^{-3} \mathrm{eV}^2/c^4$.

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K. Abe, R. Akutsu, A. Ali, J. Amey, C. Andreopoulos, L. Anthony, M. Antonova, S. Aoki, A. Ariga, Y. Ashida, Y. Azuma, S. Ban, M. Barbi, G. J. Barker, G. Barr, C. Barry, M. Batkiewicz, F. Bench, V. Berardi, S. Berkman, R. M. Berner, L. Berns, S. Bhadra, S. Bienstock, A. Blondel, S. Bolognesi, B. Bourguille, S. B. Boyd, D. Brailsford, A. Bravar, C. Bronner, M. Buizza Avanzini, J. Calcutt, T. Campbell, S. Cao, S. L. Cartwright, M. G. Catanesi, A. Cervera, A. Chappell, C. Checchia, D. Cherdack, N. Chikuma, G. Christodoulou, J. Coleman, G. Collazuol, D. Coplowe, A. Cudd, A. Dabrowska, G. De Rosa, T. Dealtry, P. F. Denner, S. R. Dennis, C. Densham, F. Di Lodovico, N. Dokania, S. Dolan, O. Drapier, K. E. Duffy, J. Dumarchez, P. Dunne, S. Emery-Schrenk, A. Ereditato, P. Fernandez, T. Feusels, A. J. Finch, G. A. Fiorentini, G. Fiorillo, C. Francois, M. Friend, Y. Fujii, R. Fujita, D. Fukuda, Y. Fukuda, K. Gameil, C. Giganti, F. Gizzarelli, T. Golan, M. Gonin, D. R. Hadley, L. Haegel, J. T. Haigh, P. Hamacher-Baumann, D. Hansen, J. Harada, M. Hartz, T. Hasegawa, N. C. Hastings, T. Hayashino, Y. Hayato, A. Hiramoto, M. Hogan, J. Holeczek, F. Hosomi, A. K. Ichikawa, M. Ikeda, J. Imber, T. Inoue, R. A. Intonti, T. Ishida, T. Ishii. 2018-07-20. Search for CP violation in Neutrino and Antineutrino Oscillations by the T2K experiment with $2.2\times10^{21}$ protons on target. https://doi.org/10.1103/physrevlett.121.171802

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