Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam

• Published in: Physical review letters Vol. 107; no. 4; p. 041801
• Main Authors: Abe, K, Abgrall, N, Aihara, H, Ariga, A, Ariga, T, Badertscher, A, Barker, G J, Bass, M, Berardi, V, Bouchez, J, Cazes, A, Cervera, A, Coleman, W, Collazuol, G, Curioni, A, Das, R, Davies, G S, Di Lodovico, F, Dore, U, Dufour, F, Dumarchez, J, Dytman, S, Escudero, L, Giffin, S, Giganti, C, Goldhaber, M, Gomez-Cadenas, J J, Gumplinger, P, Hastings, N C, Hatzikoutelis, A, Hayato, Y, Helmer, R L, Henderson, R, Horikawa, S, Hyndman, A, Ikeda, M, Ilic, J, Imber, J, Ives, S J, Jung, C K, Kirby, B, Kisiel, J, Kogan, G, Kormos, L L, Korzenev, A, Kowalik, K, Kravtsov, V, Kudenko, Y, Kulkarni, N, Laveder, M, Lee, K P, Le, P T, Litos, M, Maruyama, T, Matsuoka, K, Mavrokoridis, K, Mazzucato, E, McFarland, K S, Metelko, C, Mezzetto, M, Miller, C A, Mizouchi, K, Muir, A, Murakami, A, Murdoch, M, Murphy, S, Myslik, J, Nakayama, S, Nishikawa, K, Obayashi, Y, Ohhata, H, Okumura, K, Oyama, Y, Ozaki, T, Payne, D, Poplawska, E, Radicioni, E, Sabouri, S, Sekiya, H, Shiozawa, M, Smith, R J, Stahl, A, Stamoulis, P, Sulej, R, Tanaka, K, Tanaka, M, Tashiro, K, Taylor, I, Totsuka, Y, Tzanov, M, Wachala, T, Walding, J J, Waldron, A V, Wang, J, Weber, A, Wikström, G, Wilson, R J, Yamada, Y, Yen, S, Zimmerman, E D
• Format: Journal Article
• Language: English
• Published: United States 22.07.2011
• ISSN: 1079-7114
• DOI: 10.1103/physrevlett.107.041801

The T2K experiment observes indications of ν(μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Δm(23)(2)| = 2.4×10(-3)  eV(2), sin(2)2θ(23) = 1 and sin(2)2θ(13) = 0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2θ(13) < 0.28(0.34) for δ(CP) = 0 and a normal (inverted) hierarchy.