On the statistical treatment of the Cabibbo angle anomaly
On the statistical treatment of the Cabibbo angle anomaly
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DOI：
10.1007/jhep07(2020)068
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发表时间：
2019-11
影响因子：
5.4
通讯作者：
Y. Grossman;E. Passemar;S. Schacht
中科院分区：
文献类型：
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作者：
Y. Grossman;E. Passemar;S. Schacht
本文指出，从Γ（K→ πlν）、Γ（K→ lν）/Γ（π→ lν）比值和核β衰变中提取的Cabibbo角相等性的检验与Cabibbo-Kobayashi-Maskawa（CKM）矩阵的第一行么正性的检验是不同的.原因是CKM么正性检验只涉及两个参数，而标准模型（SM）所要求的Cabibbo角普适性拟合优度评估的自由度等于测量次数减1。除了SM之外，所有不同的过程原则上都可以给出不同的Cabibbo角。因此，两个测试之间的差异变得相关，从三个可观测值开始，给出相互紧张的卡比博角的结果。根据目前的数据，根据对核β衰变的处理，我们发现新物理学在5. 1 σ或3。6 σ，而CKM么正性在4处被拒绝。8σ或3。0σ。我们认为，最好的方法来测试的SM是测试的Cabibbo角的平等，因为CKM酉性只是一个方面的SM。
We point out that testing the equality of the Cabibbo angle as extracted from Γ (K→ πlν), the ratio Γ (K→ lν)/Γ (π→ lν) and nuclear β decays is not identical to a test of first row unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. The reason is that a CKM unitarity test involves only two parameters, while the degrees of freedom for the assessment of the goodness-of-fit of the universality of the Cabibbo angle entailed by the Standard Model (SM) is equal to the number of measurements minus one. Beyond the SM all different processes could in principle give different Cabibbo angles. Consequently, the difference between the two tests becomes relevant starting from three observables giving results for the Cabibbo angle that are in tension with each other. With current data, depending on the treatment of the nuclear β decays, we find that New Physics is favored over the SM at 5. 1 σ or 3. 6 σ while CKM unitarity is rejected at 4. 8σ or 3. 0σ, respectively. We argue that the best method to test the SM is to test the equality of the Cabibbo angle, because CKM unitarity is only one aspect of the SM.