论文标题
第二次Katrin测量活动中改进的EV级无菌性中性限制
Improved eV-scale Sterile-Neutrino Constraints from the Second KATRIN Measurement Campaign
论文作者
论文摘要
我们介绍了2019年第二次Katrin测量活动的轻型无菌中微子搜索的结果。接近名义活动，$ 3.76 \ times 10^6 $ tritium $β$ -Electrons在能量窗口中分析，延伸至$ 40 \ $ 40 \，$ ev，$ EV，低于tritium Endpoint，在$ e_0 = 18.57 = 18.57 \ $ kev，$ kev。我们认为$3ν+1 $ $框架具有三种活跃和一种无菌中微子风味。该分析对第四质量特征态$ m_4^2 \ sillsim1600 \，$ ev $^2 $和active-to-sterile混合$ | u_ {e4} |^2 \ gtrsim 6 \ times 10^{ - 3} $。由于未观察到无菌 - 中性信号，因此我们在$ m_4^2 $和$ | u_ {e4} |^2 $ $ 95 \，$ 95 \，$％c.l.上提供了改进的排除轮廓。我们的结果取代了Mainz和Troitsk实验的限制。此外，我们能够在很大程度上排除反应堆抗毒剂和镀膜异常的大$Δm_{41}^2 $解决方案。最近，最佳合作重申了后者，可以用大型混合的无菌中微子来解释。虽然小$Δm_{41}^2 $的其余解决方案主要被短基线反应堆实验所排除，但Katrin是唯一正在进行的实验室实验，可以通过强大的频谱形状分析对大$ΔM_{41}^2 $ jumu的相关溶液敏感。
We present the results of the light sterile neutrino search from the second KATRIN measurement campaign in 2019. Approaching nominal activity, $3.76 \times 10^6$ tritium $β$-electrons are analyzed in an energy window extending down to $40\,$eV below the tritium endpoint at $E_0 = 18.57\,$keV. We consider the $3ν+1$ framework with three active and one sterile neutrino flavor. The analysis is sensitive to a fourth mass eigenstate $m_4^2\lesssim1600\,$eV$^2$ and active-to-sterile mixing $|U_{e4}|^2 \gtrsim 6 \times 10^{-3}$. As no sterile-neutrino signal was observed, we provide improved exclusion contours on $m_4^2$ and $|U_{e4}|^2$ at $95\,$% C.L. Our results supersede the limits from the Mainz and Troitsk experiments. Furthermore, we are able to exclude the large $Δm_{41}^2$ solutions of the reactor antineutrino and gallium anomalies to a great extent. The latter has recently been reaffirmed by the BEST collaboration and could be explained by a sterile neutrino with large mixing. While the remaining solutions at small $Δm_{41}^2$ are mostly excluded by short-baseline reactor experiments, KATRIN is the only ongoing laboratory experiment to be sensitive to relevant solutions at large $Δm_{41}^2$ through a robust spectral shape analysis.
