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arXiv · 1106.2822

Indication of Electron Neutrino Appearance from an Accelerator-produced Off-axis Muon Neutrino Beam

T2K Collaboration·K. Abe·N. Abgrall·Y. Ajima·H. Aihara·J. B. Albert·C. Andreopoulos·B. Andrieu·S. Aoki·O. Araoka·J. Argyriades·A. Ariga·T. Ariga·S. Assylbekov·D. Autiero·A. Badertscher·M. Barbi·G. J. Barker·G. Barr·M. Bass·F. Bay·S. Bentham·V. Berardi·B. E. Berger·I. Bertram·M. Besnier·J. Beucher·D. Beznosko·S. Bhadra·F. d. M. Blaszczyk·A. Blondel·C. Bojechko·J. Bouchez·S. B. Boyd·A. Bravar·C. Bronner·D. G. Brook-Roberge·N. Buchanan·H. Budd·D. Calvet·S. L. Cartwright·A. Carver·R. Castillo·M. G. Catanesi·A. Cazes·A. Cervera·C. Chavez·S. Choi·G. Christodoulou·J. Coleman·W. Coleman·G. Collazuol·K. Connolly·A. Curioni·A. Dabrowska·I. Danko·R. Das·G. S. Davies·S. Davis·M. Day·G. DeRosa·J. P. A. M. de Andre·P. dePerio·A. Delbart·C. Densham·F. DiLodovico·S. DiLuise·P. Dinh Tran·J. Dobson·U. Dore·O. Drapier·F. Dufour·J. Dumarchez·S. Dytman·M. Dziewiecki·M. Dziomba·S. Emery·A. Ereditato·L. Escudero·L. S. Esposito·M. Fechner·A. Ferrero·A. J. Finch·E. Frank·Y. Fujii·Y. Fukuda·V. Galymov·F. C. Gannaway·A. Gaudin·A. Gendotti·M. George·S. Giffin·C. Giganti·K. Gilje·T. Golan·M. Goldhaber·J. J. Gomez-Cadenas·M. Gonin·N. Grant·A. Grant
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Abstract

The T2K experiment observes indications of $\nu_\mu\rightarrow \nu_e$ appearance in data accumulated with $1.43\times10^{20}$ protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with $|\Delta m_{23}^2|=2.4\times10^{-3}$ eV$^2$, $\sin^2 2\theta_{23}=1$ and $\sin^2 2\theta_{13}=0$, the expected number of such events is 1.5$\pm$0.3(syst.). Under this hypothesis, the probability to observe six or more candidate events is 7$\times10^{-3}$, equivalent to 2.5$\sigma$ significance. At 90% C.L., the data are consistent with 0.03(0.04)$<\sin^2 2\theta_{13}<$ 0.28(0.34) for $\delta_{\rm CP}=0$ and a normal (inverted) hierarchy.

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T2K Collaboration, K. Abe, N. Abgrall, Y. Ajima, H. Aihara, J. B. Albert, C. Andreopoulos, B. Andrieu, S. Aoki, O. Araoka, J. Argyriades, A. Ariga, T. Ariga, S. Assylbekov, D. Autiero, A. Badertscher, M. Barbi, G. J. Barker, G. Barr, M. Bass, F. Bay, S. Bentham, V. Berardi, B. E. Berger, I. Bertram, M. Besnier, J. Beucher, D. Beznosko, S. Bhadra, F. d. M. Blaszczyk, A. Blondel, C. Bojechko, J. Bouchez, S. B. Boyd, A. Bravar, C. Bronner, D. G. Brook-Roberge, N. Buchanan, H. Budd, D. Calvet, S. L. Cartwright, A. Carver, R. Castillo, M. G. Catanesi, A. Cazes, A. Cervera, C. Chavez, S. Choi, G. Christodoulou, J. Coleman, W. Coleman, G. Collazuol, K. Connolly, A. Curioni, A. Dabrowska, I. Danko, R. Das, G. S. Davies, S. Davis, M. Day, G. DeRosa, J. P. A. M. de Andre, P. dePerio, A. Delbart, C. Densham, F. DiLodovico, S. DiLuise, P. Dinh Tran, J. Dobson, U. Dore, O. Drapier, F. Dufour, J. Dumarchez, S. Dytman, M. Dziewiecki, M. Dziomba, S. Emery, A. Ereditato, L. Escudero, L. S. Esposito, M. Fechner, A. Ferrero, A. J. Finch, E. Frank, Y. Fujii, Y. Fukuda, V. Galymov, F. C. Gannaway, A. Gaudin, A. Gendotti, M. George, S. Giffin, C. Giganti, K. Gilje, T. Golan, M. Goldhaber, J. J. Gomez-Cadenas, M. Gonin, N. Grant, A. Grant. 2011-06-14. Indication of Electron Neutrino Appearance from an Accelerator-produced Off-axis Muon Neutrino Beam. https://doi.org/10.1103/physrevlett.107.041801

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