论文标题
非大学$ z $耦合在解释$ v_ {us} $异常中的作用
The role of non-universal $Z$ couplings in explaining the $V_{us}$ anomaly
论文作者
论文摘要
$ v_ {us} $的张力从不同的频道（所谓的Cabibbo角异常）中解释为在$ W $ boson耦合中违反Lepton风味普遍性（LFU）的信号。我们在有效现场理论的框架中调查了这个问题，使标准模型（SM）的规格结构保持不变。我们介绍了量规不变的尺寸-6有效的操作员，将希格斯双线搭配到叶子，从而为electroweak仪表玻色子的耦合提供了非全宇宙树级的贡献。由于$ su（2）_l $量规对称，因此在受新$ W $耦合影响的$ v_ {us} $测量与Electroweak Precision测量结果之间产生了张力，这些测量也受到新$ z $ couplings的影响。我们表明，可以通过允许$ z $ boson的其他量规不变耦合耦合来缓解这种张力，并找到Wilson-coeffiffiffife flace的当前数据所指示的最佳区域。我们用涉及矢量样的Lepton（VLL）模型的SM的最小扩展的示例来说明我们的模型无关的结果。我们指出的是，将Higgs Doublet耦合到瘦小的尺寸-6操作员可能会影响$ H \ \ττ$衰减的速率，但是对于最小VLL模型而言，这种效果仅限于小于％的水平。
The tension among measurements of $V_{us}$ from different channels, the so-called Cabibbo Angle Anomaly, can be interpreted as a signal of lepton flavor universality (LFU) violation in the $W$ boson couplings. We investigate this issue in the framework of effective field theory, keeping the gauge structure of the Standard Model (SM) unchanged. We introduce gauge-invariant dimension-6 effective operators that couple the Higgs doublet to leptons, thereby giving non-universal tree-level contributions to the couplings of electroweak gauge bosons. Due to the $SU(2)_L$ gauge symmetry, a tension arises between the $V_{us}$ measurements that are affected by new $W$ couplings, and the electroweak precision measurements, which are also affected by the new $Z$ couplings. We show that this tension can be alleviated by allowing additional sources of gauge-invariant couplings of $Z$ boson to left- or right-handed leptons, and find the optimal regions indicated by the current data in the Wilson-coefficient space. We illustrate our model-independent results with the examples of minimal extensions of the SM involving the vector-like lepton (VLL) models. We point out that dimension-6 operators coupling the Higgs doublet to leptons can affect the rate of $h \to ττ$ decay significantly in general, however this effect is restricted to less than a per cent level for the minimal VLL models.
