Observation of electron neutrino appearance in a muon neutrino beam.
Observation of electron neutrino appearance in a muon neutrino beam.
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DOI：
10.1103/physrevlett.112.061802
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发表时间：
2013-11
影响因子：
8.6
通讯作者：
K. Abe;J. Ádám;H. Aihara;T. Akiri;C. Andreopoulos;S. Aoki;A. Ariga;T. Ariga;S. Assylbekov-S.-Assylbek
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文献类型：
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作者：
K. Abe;J. Ádám;H. Aihara;T. Akiri;C. Andreopoulos;S. Aoki;A. Ariga;T. Ariga;S. Assylbekov-S.-Assylbek
T2 K实验观测到了从295公里处的超级神冈探测器产生的μ子中微子束中出现的电子中微子，峰值能量为0.6 GeV。总共检测到28个电子中微子事件，其能量分布与外观信号一致，与4.92±0.55个预期背景事件相比，对应于7.3σ的显著性。在Pontecorvo-Maki-Nakagawa-Sakata混合模型中，电子中微子的出现信号取决于几个参数，包括三个混合角θ12，θ23，θ13，质量差Δm（32）（2）和CP破坏相δ（CP）。在这个中微子振荡的情况下，假设|Δm（2）|=2.4×10（-3）eV（2），sin（2）θ（23）=0.5，Δm322>0（Δm（32）（2）<0），在δ（CP）=0时得到sin（2）2θ（13）=0.140（-0.032）（+0.038）（0.170（-0.037）（+0.045）的最佳拟合值。结合目前对振荡参数的最佳认识，包括反应堆实验中θ（13）的世界平均值，在90%C. L.
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 Δm(32)(2) and a CP violating phase δ(CP). In this neutrino oscillation scenario, assuming |Δm(32)(2)|=2.4×10(-3) eV(2), sin(2)θ(23)=0.5, and Δm322>0 (Δm(32)(2)<0), a best-fit value of sin(2)2θ(13)=0.140(-0.032)(+0.038) (0.170(-0.037)(+0.045)) is obtained at δ(CP)=0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ(13) from reactor experiments, some values of δ(CP) are disfavored at the 90% C.L.