Abe, K. and Bentham, S. and Bertram, I. and Finch, Alexander and Grant, N. and Hatzikoutelis, A. and Maryon, T. and Kormos, Laura and , T2K Collaboration (2011) Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam. Physical review letters, 107 (4). ISSN 1079-7114
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Abstract
The T2K experiment observes indications of nu(mu) -> nu(mu) e appearance in data accumulated with 1.43 x 10(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 x 10(-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 +/- 0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7 x 10(-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(CP) = 0 and a normal (inverted) hierarchy.