Search for heavy neutrinos with the T2K near detector ND280
Search for heavy neutrinos with the T2K near detector ND280
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DOI：
10.1103/physrevd.100.052006
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发表时间：
2019-02
影响因子：
5
通讯作者：
K. Abe;R. Akutsu;A. Ali;C. Andreopoulos;L. Anthony;M. Antonova;S. Aoki;A. Ariga;Y. Ashida-Y.-Ashid
中科院分区：
文献类型：
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作者：
K. Abe;R. Akutsu;A. Ali;C. Andreopoulos;L. Anthony;M. Antonova;S. Aoki;A. Ariga;Y. Ashida-Y.-Ashid
本文报道了利用T2 K实验的离轴近探测器ND 280寻找质量在140 < M_N < 493$ MeV/c^2 $范围内的重中微子的情况。这些粒子可以由标准中微子束中的K介子衰变产生，然后在ND 280中衰变。考虑的衰变模式是$N \to \ell^{\pm}_{\alpha} \pi^{\mp}$和$N \to \ell^+_{\alpha} \ell^-_{\beta} \nu（\bar\nu）$（$\alpha，\beta=e，\mu$）。已使用ND 280的时间投影室搜索此类事件，其中背景已减少到所有通道中当前数据集中的两个事件以下。在信号区未观察到过量。本文应用贝叶斯统计方法，提取了重中微子与电子流、μ子流和τ流混合元素的上限值（U_e^2 $，U_{\mu}^2$，U_{\tau}^2$）与重中微子质量的函数关系，如在90\%C. L时U_e^2 < 10^{-9}$。质量为390兆电子伏/立方厘米。这些限制与以前的实验是竞争性的。
This paper reports on the search for heavy neutrinos with masses in the range $140 < M_N < 493$ MeV/c$^2$ using the off-axis near detector ND280 of the T2K experiment. These particles can be produced from kaon decays in the standard neutrino beam and then subsequently decay in ND280. The decay modes under consideration are $N \to \ell^{\pm}_{\alpha} \pi^{\mp}$ and $N \to \ell^+_{\alpha} \ell^-_{\beta} \nu (\bar\nu)$ ($\alpha,\beta=e,\mu$). A search for such events has been made using the Time Projection Chambers of ND280, where the background has been reduced to less than two events in the current dataset in all channels. No excess has been observed in the signal region. A combined Bayesian statistical approach has been applied to extract upper limits on the mixing elements of heavy neutrinos to electron-, muon- and tau- flavoured currents ($U_e^2$, $U_{\mu}^2$, $U_{\tau}^2$) as a function of the heavy neutrino mass, e.g. $U_e^2 < 10^{-9}$ at $90\%$ C.L. for a mass of $390$ MeV/c$^2$. These constraints are competitive with previous experiments.