arXiv 1802.062772018-02-17nucl-ex

中子寿命、暗物质和寻找无菌中微子

Neutron lifetime, dark matter and search for sterile neutrino

A. P. Serebrov, R. M. Samoilov, I. A. Mitropolsky, A. M. Gagarsky

备注：: 20 pages, 18 figures

摘要：

本文综述了中子寿命的实验测量方法。最新的引力阱（PNPI NRC KI）和磁阱（LANL，USA）测量证实了PNPI 2005年的结果。超冷中子贮存的测量结果是一致的，然而，与$3.5σ$的束流实验（1%的衰变概率），这是在文献中讨论的“中子异常”，以及部分地解释为暗物质衰变的想法有出入。第二部分讨论了反应堆反中微子异常现象，它是指反应堆反中微子通量的测量值与$3σ$的计算值相差6.6%。本文建议的具体特点在于，这两种异常可以用同一个现象来解释，即在一个中子和一个质量$m_{n'}$略小于普通中子质量$m_n$的暗物质$n{\rightarrow}n'$的中子之间的重子扇区振荡。所提出的模型的计算需要一个自由参数：质量差$m_n-m_{n'}$如果一个标准化的概率振荡的自由中子的“中子异常”的1%，然后，成功地解释了6.6%的中子异常的计算，可以确定质量差。根据初步估计，质量差为$m_n-m_{n'}{\approx}$ 3 MeV。然而，对裂变碎片中发生的同位素累积产率进行了分析，未证实存在额外衰变通道的可能性，该通道发射质量差为$m_n-m_{n'}{\approx}$ 3 MeV的暗物质中子。分析的结果是结论，镜像中子的质量差$m_n-m_{n'} {\geq}$ 3 MeV的区域是封闭的。质量差为$m_n-m_{n'}{\leq}$ 2 MeV的区域并不封闭。

英文摘要：

A review is focused on experimental measurements on neutron lifetime. The latest measurements with a gravitational trap (PNPI NRC KI) and a magnetic trap (LANL, USA) confirmed PNPI result of 2005. The results of measurements with storage of ultra cold neutrons are in agreement, yet, there is discrepancy with a beam experiment by $3.5σ$ (1% of decay probability), which is discussed in literature as "neutron anomaly" along with the ideas of explaining it by decay into dark matter partially. The second part of the paper is devoted to so called "reactor antineutrino anomaly", which refers to deficiency of the measured flux of antineutrino from reactor in respect to the calculated flux by $3σ$(deviation by 6.6%). Specific feature of the proposal in this paper lies in the fact that both anomalies can be accounted for by one and the same phenomenon of oscillation in baryon sector between a neutron and a neutron of dark matter $n{\rightarrow}n'$ with mass $m_{n'}$, somewhat less than mass $m_n$ of an ordinary neutron. Calculations of the proposed model require one free parameter: mass difference $m_n-m_{n'}$ if one normalizes probability of oscillations for a free neutron on "neutron anomaly" 1%, then, having succeeded to interpret 6.6% of neutron anomaly in calculations, one can determine mass difference. According to preliminary estimations, the mass difference is $m_n-m_{n'}{\approx}$ 3 MeV. However, the analysis of cumulative yields of isotopes occurs in fission fragments was performed and it does not confirm possibility of existence of additional decay channel with emission of dark matter neutron with mass difference $m_n-m_{n'}{\approx}$ 3 MeV. The result of the analysis is the conclusion that for mirror neutrons the region of the mass difference $m_n-m_{n'} {\geq}$ 3 MeV is closed. The region of the mass difference $m_n-m_{n'}{\leq}$ 2 MeV turned out to be not closed.

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英文摘要：

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