论文标题
无菌中微子振荡搜索反应堆的统计解释
Statistical interpretation of sterile neutrino oscillation searches at reactors
论文作者
论文摘要
目前正在进行大量的实验努力，以测试由于各种反应堆中微子实验数据中的EV级无菌中微子而导致的持续提示。这些提示的统计意义的评估通常基于Wilks的定理，从而假设对数可能为$χ^2 $分布。然而，众所周知，对于中微子振荡实验，未实现Wilks定理有效性的先决条件。在这项工作中，我们得出了一种简单的渐近形式，即基于将问题重新解释为拟合白色高斯噪声的实际分布的实际分布。从这种形式主义中，我们表明，即使没有无菌中微子，混合角的最大似然估计值的期望值仍然是非零的，而随之而来的是对数可能的大值。然后，通过玩具反应器实验的数值模拟来证实我们的分析结果。最后，我们将此框架应用于中微子-4实验的数据，并表明在2.6 \，$σ$级别上拒绝了无振荡的零假设，而3.2 \，在Wilks的假设中获得的3.2 \，$σ$。
A considerable experimental effort is currently under way to test the persistent hints for oscillations due to an eV-scale sterile neutrino in the data of various reactor neutrino experiments. The assessment of the statistical significance of these hints is usually based on Wilks' theorem, whereby the assumption is made that the log-likelihood is $χ^2$-distributed. However, it is well known that the preconditions for the validity of Wilks' theorem are not fulfilled for neutrino oscillation experiments. In this work we derive a simple asymptotic form of the actual distribution of the log-likelihood based on reinterpreting the problem as fitting white Gaussian noise. From this formalism we show that, even in the absence of a sterile neutrino, the expectation value for the maximum likelihood estimate of the mixing angle remains non-zero with attendant large values of the log-likelihood. Our analytical results are then confirmed by numerical simulations of a toy reactor experiment. Finally, we apply this framework to the data of the Neutrino-4 experiment and show that the null hypothesis of no-oscillation is rejected at the 2.6\,$σ$ level, compared to 3.2\,$σ$ obtained under the assumption that Wilks' theorem applies.
