论文标题
$ d^\ ast $偏振是对$ b \ tocτ\barν_τ$ transition中新物理学的附加约束
$D^\ast$ Polarization as an Additional Constraint on New Physics in the $b\to cτ\barν_τ$ Transition
论文作者
论文摘要
半衰减衰减的分支分数的测量值$ b \ to d^{（*）}τ\barν_τ$和$ b_c \ to j/ψτ\barν_τ$系统地超出了标准模型（SM）预测，指出了可能违反lepate leptate lepton flaise fluestality的可能信号。可以使用由四弗里尔式操作员和相应的威尔逊系数构建的一般有效的哈密顿量探测在这些通道中实现的新物理学的未知来源。以前，对这些威尔逊系数的约束主要是从分支分数的实验数据中获得的。同时，仅在理论上研究了极化。随着更多的实验数据的可用，尤其是关于tau和$ d^*$梅森的两极分化的情况，情况发生了变化。在这项研究中，我们讨论了新数据对整体情况的含义。然后，我们使用协变量夸克模型中的所有HADRONIC形式尺寸将它们包括在Wilson系数的更新拟合中。我们的形式因素的使用提供了与文献中的分析相关的分析。研究了几种新物理方案，并提供了相应的理论预测，这些预测对于将来的实验研究很有用。
Measurements of the branching fractions of the semileptonic decays $B\to D^{(*)}τ\barν_τ$ and $B_c\to J/ψτ\barν_τ$ systematically exceed the Standard Model (SM) predictions, pointing to possible signals of new physics that can violate lepton flavor universality. The unknown origin of new physics realized in these channels can be probed using a general effective Hamiltonian constructed from four-fermion operators and the corresponding Wilson coefficients. Previously, constraints on these Wilson coefficients were obtained mainly from the experimental data for the branching fractions. Meanwhile, polarization observables were only theoretically studied. The situation has changed with more experimental data having become available, particularly those regarding the polarization of the tau and the $D^*$ meson. In this study, we discuss the implications of the new data on the overall picture. We then include them in an updated fit of the Wilson coefficients using all hadronic form factors from our covariant constituent quark model. The use of our form factors provides an analysis independent of those in the literature. Several new-physics scenarios are studied with the corresponding theoretical predictions provided, which are useful for future experimental studies.
