Publications
Publication Information
| Title | On the Statistical Treatment of the Cabibbo Angle Anomaly |
| Authors | Yuval Grossman, Stefan Schacht, Emilie Passemar |
| JLAB number | JLAB-THY-19-3050 |
| LANL number | arXiv:1911.07821 |
| Other number | DOE/OR/23177-4780 |
| Document Type(s) | (Journal Article) |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
| Other Funding: | National Science Foundation |
|
Journal Compiled for Journal of High Energy Physics Volume 2020 Page(s) 68 Refereed | |
| Publication Abstract: | We point out that testing the equality of the Cabibbo angle as extracted from $\Gamma(K\rightarrow \pi l\nu)$, the ratio $\Gamma(K\rightarrow l\nu)/\Gamma(\pi\rightarrow l\nu)$ and nuclear $\beta$ 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 $\beta$ decays, we find that New Physics is favored over the SM at $5.1\,\sigma$ or $3.6\,\sigma$ while CKM unitarity is rejected at $4.8\sigma$ or $3.0\sigma$, 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. |
| Experiment Numbers: | other |
| Group: | THEORY CENTER |
| Document: | |
| DOI: | https://doi.org/10.1007/JHEP07(2020)068 |
| Accepted Manuscript: | Grossman2020_Article_OnTheStatisticalTreatmentOfThe.pdf |
| Supporting Documents: | |
| Supporting Datasets: | |