Search for sterile neutrino mixing in the MINOS long baseline experiment
Search for sterile neutrino mixing in the MINOS long baseline experiment
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DOI：
10.1103/physrevd.81.052004
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发表时间：
2010-01
影响因子：
5
通讯作者：
The Minos Collaboration
中科院分区：
文献类型：
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作者：
The Minos Collaboration
使用NUMI中微子束中MINOS探测器记录的中性流相互作用数据，报告了在735 km基线上寻找活性中微子物质的组合通量的耗尽。根据涉及三种已知中微子味的中微子振荡数据的传统解释，这种耗尽是不可能的。耗尽可能是假设的无相互作用的无菌中微子振荡或衰变的标志，现有数据没有排除这种情况。利用3.18×10^（20）质子对靶的照射，在MINOS远探测器上重建了候选中性流反应的可见能谱。将该谱与从类似选择的近探测器样品推断的谱进行比较表明，在带电相互作用数据中观察到的消失的ν μ通量部分中，在90%置信水平（C.L.）下，可以转化为无菌状态的部分小于52%。通过将数据拟合到各种模型中，验证了活性中微子通过振荡与单个无菌中微子混合的假设。在所考虑的特殊四中微子模型中，混合角θ_（24）和θ_（34）在90%C. L.被限制在小于11°和56°，分别还研究了活跃中微子衰变为惰性中微子的可能性。在5.4标准偏差下排除了没有振荡的纯中微子衰变。在中微子振荡的同时，活动中微子衰变到无菌态的情况下，在90%C. L时，中微子衰变寿命τ_3/m_3>2.1×10^（-12）s/eV。
A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18×10^(20) protons on target in which neutrinos of energies between ∼500 MeV and 120 GeV are produced predominantly as ν_μ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ν_μ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles θ_(24) and θ_(34) are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime τ_3/m_3>2.1×10^(-12) s/eV at 90% C.L.