利用 T2K 实验在靶上 2.2×10^{21} 个质子中寻找中微子和反中微子振荡中的 CP 破坏。
Search for CP Violation in Neutrino and Antineutrino Oscillations by the T2K Experiment with 2.2×10^{21} Protons on Target.
机构信息
University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan.
University of Tokyo, Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, Kashiwa, Japan.
出版信息
Phys Rev Lett. 2018 Oct 26;121(17):171802. doi: 10.1103/PhysRevLett.121.171802.
The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of 14.7(7.6)×10^{20} protons on target in the neutrino (antineutrino) mode, 89 ν_{e} candidates and seven anti-ν_{e} candidates are observed, while 67.5 and 9.0 are expected for δ_{CP}=0 and normal mass ordering. The obtained 2σ confidence interval for the CP-violating phase, δ_{CP}, does not include the CP-conserving cases (δ_{CP}=0, π). The best-fit values of other parameters are sin^{2}θ_{23}=0.526_{-0.036}^{+0.032} and Δm_{32}^{2}=2.463_{-0.070}^{+0.071}×10^{-3} eV^{2}/c^{4}.
T2K 实验测量了在加速器产生的中微子和反中微子束中μ子中微子消失和电子中微子出现。在中微子（反中微子）模式下，T2K 实验的目标质子靶暴露量为 14.7（7.6）×10^{20}，观察到 89 个 ν_{e}候选事例和 7 个 anti-ν_{e}候选事例，而在 δ_{CP}=0 和正常质量顺序的情况下，预计分别为 67.5 和 9.0。CP 破坏相 δ_{CP}的 2σ置信区间不包括 CP 守恒情况（δ_{CP}=0，π）。其他参数的最佳拟合值为 sin^{2}θ_{23}=0.526_{-0.036}^{+0.032} 和 Δm_{32}^{2}=2.463_{-0.070}^{+0.071}×10^{-3} eV^{2}/c^{4}。
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