Observation of electron neutrino appearance in a muon neutrino beam

K. Abe, J. Adam, H. Aihara, T. Akiri, C. Andreopoulos, S. Aoki, A. Ariga, T. Ariga, S. Assylbekov, D. Autiero, M. Barbi, G. J. Barker, G. Barr, M. Bass, M. Batkiewicz, F. Bay, S. W. Bentham, V. Berardi, B. E. Berger, S. BerkmanI. Bertram, S. Bhadra, F. D.M. Blaszczyk, A. Blondel, C. Bojechko, S. Bordoni, S. B. Boyd, D. Brailsford, A. Bravar, C. Bronner, N. Buchanan, R. G. Calland, J. Caravaca Rodriguez, S. L. Cartwright, R. Castillo, M. G. Catanesi, A. Cervera, D. Cherdack, G. Christodoulou, A. Clifton, J. Coleman, S. J. Coleman, G. Collazuol, K. Connolly, L. Cremonesi, A. Dabrowska, I. Danko, R. Das, S. Davis, P. De Perio, T2K Collaboration

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424 Citations (Scopus)


The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3σ when compared to 4.92 ± 0.55 expected background events. In the Pontecorvo-Maki-Nakagawa-Sakata mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles θ12, θ23, θ13, a mass difference Δm2 32and a CP violating phase δCP. In this neutrino oscillation scenario, assuming |Δm2 32| = 2.4 × 10-3eV2, sin2θ23= 0.5, and Δm2 32> 0 (Δm2 32< 0), a best-fit value of sin213= 0.140+0.038 -0.032(0.170+0.045 -0.037) is obtained at δCP= 0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ13from reactor experiments, some values of δCPare disfavored at the 90% C.L.

Original languageEnglish
Article number061802
JournalPhysical Review Letters
Issue number6
Publication statusPublished - Feb 10 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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