Constraints on θ 13 from a three-flavor oscillation analysis of reactor antineutrinos at KamLAND
We present new constraints on the neutrino oscillation parameters Δm212, θ 12 , and θ 13 from a three-flavor analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49×1032 target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis (θ 13 =0) of the KamLAND and solar data yields the best-fit values tan 2θ 12 =0.444-0.030+0.036 and Δm212=7.50-0.20+0.19×10 - 5eV2; a three-flavor analysis with θ 13 as a free parameter yields the best-fit values tan 2θ 12 =0.452-0.033+0.035, Δm212=7.50-0.20+0.19×10 - 5eV2, and sin 2θ 13 =0.020-0.016+0.016. This θ 13 interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global θ 13 analysis, incorporating the CHOOZ, atmospheric, and accelerator data, which indicates sin 2θ 13 =0.009-0. 007+0.013. A nonzero value is suggested, but only at the 79% C.L. © 2011 American Physical Society.
Gando, A; Gando, Y; Ichimura, K; Ikeda, H; Inoue, K; Kibe, Y; Kishimoto, Y; Koga, M; Minekawa, Y; Mitsui, T; Morikawa, T; Nagai, N; Nakajima, K; Nakamura, K; Narita, K; Shimizu, I; Shimizu, Y; Shirai, J; Suekane, F; Suzuki, A; Takahashi, H; Takahashi, N; Takemoto, Y; Tamae, K; Watanabe, H; Xu, BD; Yabumoto, H; Yoshida, H; Yoshida, S; Enomoto, S; Kozlov, A; Murayama, H; Grant, C; Keefer, G; Piepke, A; Banks, TI; Bloxham, T; Detwiler, JA; Freedman, SJ; Fujikawa, BK; Han, K; Kadel, R; O'Donnell, T; Steiner, HM; Dwyer, DA; McKeown, RD; Zhang, C; Berger, BE; Lane, CE; Maricic, J; Miletic, T; Batygov, M; Learned, JG; Matsuno, S; Sakai, M; Horton-Smith, GA; Downum, KE; Gratta, G; Efremenko, Y; Perevozchikov, O; Karwowski, HJ; Markoff, DM; Tornow, W; Heeger, KM; Decowski, MP
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