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arXiv 2407.06145hep-ph
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从遍举(半)轻子 charm 衰变约束 $|V_{cs}|$ 与超出标准模型的物理

Constraining $|V_{cs}|$ and physics beyond the Standard Model from exclusive (semi)leptonic charm decays

Carolina Bolognani, Méril Reboud, Danny van Dyk, K. Keri Vos

AI总结:

研究遍举(半)轻子 charm 衰变数据,通过色散边界考虑强子矩阵元关联,在标准模型下得到 $|V_{cs}|$ 结果并发现 CKM 幺正性偏差,同时对超出标准模型的(赝)标量、张量效应及 CP 破坏右手流给出约束。

摘要:

我们在标准模型及超出标准模型的框架下,研究了遍举轻子型和半轻子型 $c\to s\boldsymbol{\text{ℓ}}^+ν$ 衰变的现有数据。我们的分析通过应用色散边界,考虑了相关强子矩阵元之间的理论关联。全局分析发现,色散边界总体上得到很好满足,且对卡比博-小林-益川(CKM)矩阵元 $|V_{cs}|$ 的提取仅产生轻微影响。假设标准模型动力学成立,我们得到 $|V_{cs}| = 0.957 \boldsymbol{\text{±}} 0.003$,该结果与 HFLAV/PDG 参考值 $|V_{cs}| = 0.975 \boldsymbol{\text{±}} 0.006$ 在 $2.7\boldsymbol{\text{σ}}$ 水平上兼容。我们的发现导致 CKM 矩阵的第二行和第二列幺正性关系出现显著偏差。在弱有效理论中考虑超出标准模型的贡献时,我们发现对潜在(赝)标量和张量效应的约束非常强,但数据仍允许可观的 CP 破坏右手流存在。

英文摘要:

We study the available data on exclusive leptonic and semileptonic $c\to s\ell^+ν$ decays within the Standard Model and beyond. Our analysis accounts for theory correlations between the relevant hadronic matrix elements through application of dispersive bounds. We find that, within a global analysis, the dispersive bounds are generally well respected and only mildly affect the extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|V_{cs}|$. Assuming Standard Model dynamics, we obtain $$ |V_{cs}| = 0.957 \pm 0.003\,, $$ which is compatible with the HFLAV/PDG reference value $|V_{cs}| = 0.975 \pm 0.006$ at the $2.7\,σ$ level. Our findings lead to significant deficits in the second-row and second-column unitarity relations of the CKM matrix. Allowing for beyond the SM contributions in the Weak Effective Theory, we find very strong constraints on potential (pseudo)scalar and tensor effects. However, the data still permits sizeable CP-violating right-handed currents.

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