论文标题
对非常稀有的$ k^+\rightarrowπ^+ν\barν$ decay的调查
An investigation of the very rare $K^+\rightarrowπ^+ν\barν$ decay
论文作者
论文摘要
NA62实验报告了$ k^+\rightArrowπ^+bbarν$模式的调查，该模式是从2017年在Cern SPS收集的$ K^+$衰减的样本。该实验达到了$（0.389 \ pm 0.024）\ times10^{ - 10} $的单个事件灵敏度，对应于2.2事件，假设标准模型分支比率为$（8.4 \ pm1.0）\ times10^{ - 11} $。观察到两个信号候选者的预期背景为1.5事件。结合NA62对2016年记录的较小数据集进行的类似分析的结果，该协作现在报告了$ k^+\rightArrowπ^+bar的上限为$ 1.78 \ times10^{ - 10} $，分支比例为90 \％\，Cl，Cl。与相应的68 \％\一起，$（0.48^{+0.72} _ { - 0.48}）\ times10^{ - 10} $的Cl测量是全球范围内最精确的结果，并且能够限制一些新的物理学模型，这些新的物理学模型仍然可以通过以前的测量值进行。
The NA62 experiment reports an investigation of the $K^+\rightarrowπ^+ν\barν$ mode from a sample of $K^+$ decays collected in 2017 at the CERN SPS. The experiment has achieved a single event sensitivity of $(0.389\pm 0.024)\times10^{-10}$, corresponding to 2.2 events assuming the Standard Model branching ratio of $(8.4\pm1.0)\times10^{-11}$. Two signal candidates are observed with an expected background of 1.5 events. Combined with the result of a similar analysis conducted by NA62 on a smaller data set recorded in 2016, the collaboration now reports an upper limit of $1.78\times10^{-10}$ for the $K^+\rightarrowπ^+ν\barν$ branching ratio at 90\%\,CL. This, together with the corresponding 68\%\,CL measurement of $(0.48^{+0.72 }_{-0.48})\times10^{-10}$, are currently the most precise results worldwide, and are able to constrain some New Physics models that predict large enhancements still allowed by previous measurements.
