论文标题
通过$ k_ {μ3}/k_ {μ2} $分支分数的新测量进行仔细检查CKM Unitarity
Scrutinizing CKM unitarity with a new measurement of the $K_{μ3}/K_{μ2}$ branching fraction
论文作者
论文摘要
Cabibbo-Kobayashi-Maskawa Matrix的第一行单位性的精确测试目前显示出两个有趣的紧张局势，均为$3σ$级别。首先，将$ v_ {ud} $的确定与$β$衰减与$ v_ {us} $从kaon衰变中结合在一起，这表明单位性关系赤字。同时，具有相似意义的张力在$ k _ {\ ell 2} $和$ k _ {\ ell 3} $衰减之间出现。在这封信中，我们指出的是，$ k _ {\ mu3}/k_ {μ2} $分支的水平为$ 0.2 \％$的分支将对KAON部门的实验状况产生重大影响，尤其是在$ kaon数据的全球范围内，尤其是在$ k_的情况下}单个实验。这样的测量，例如在NA62上，将进一步对标准模型以外的物理的重要限制，最著名的是右手矢量电流的作用。
Precision tests of first-row unitarity of the Cabibbo-Kobayashi-Maskawa matrix currently display two intriguing tensions, both at the $3σ$ level. First, combining determinations of $V_{ud}$ from superallowed $β$ decays with $V_{us}$ from kaon decays suggests a deficit in the unitarity relation. At the same time, a tension of similar significance has emerged between $K_{\ell 2}$ and $K_{\ell 3}$ decays. In this Letter, we point out that a measurement of the $K_{\mu3}/K_{μ2}$ branching fraction at the level of $0.2\%$ would have considerable impact on clarifying the experimental situation in the kaon sector, especially in view of tensions in the global fit to kaon data as well as the fact that the $K_{\mu2}$ channel is currently dominated by a single experiment. Such a measurement, as possible for example at NA62, would further provide important constraints on physics beyond the Standard Model, most notably on the role of right-handed vector currents.
