论文标题
贝叶斯拟合分析$ \ bar b \ d^{（*）} \ ell \barν$：$ | v_ {cb} | $确定和新物理限制
Bayesian fit analysis to full distribution data of $\bar B \to D^{(*)} \ell\barν$: $|V_{cb}|$ determination and New Physics constraints
论文作者
论文摘要
We investigate the semi-leptonic decays of $\bar B \to D^{(*)} \ell\barν$ in terms of the Heavy-Quark-Effective-Theory (HQET) parameterization for the form factors, which is described with the heavy quark expansion up to $\mathcal O(1/m_c^2)$ beyond the simple approximation considered in the original CLN parameterization.文献中首先进行了对该设置的分析，然后我们将其扩展到全面的分析中，包括（i）$ | v_ {cb} | $的同时拟合，以及HQET参数以及可用的实验完整分布数据和理论约束，以及（ii）新物理学（NP）$ v_2 $和$ t $ $ t $和$ t $和$ t $和$ t $ and $ d $ decay和dep decay和dep depay和decay的贡献。为此，我们通过使用Stan程序（用于统计计算的最先进的公共平台STAN程序进行贝叶斯拟合分析。然后，我们表明我们的$ | v_ {cb} | $ fit结果接近独家模式的PDG合并平均值，并指示角分布数据的重要性。反过来，对于$ \ text {sm} + \ text {np} $方案，我们的拟合分析发现，根据$ \ text {sm} + v_2 $和$ \ text {sm} + text {sm} + t $，根据HQET参数化模型，非零的NP贡献在最佳拟合点上受到最佳拟合点的青睐。然后，在$ \ bar b \ to d^{（*）}τ\barν$ observables中实现了一个关键功能。我们对$ \ text {sm}（+t）$中HQET参数的适合结果产生了$ r_d $的一致值，而对于$ r_ {d^*} $，与HFLAV报告中的先前SM预测相比，$ r_ {d^*} $较小。另一方面，$ \ text {sm}+v_2 $点指向$ r_d $和$ r_ {d^*} $的较小和较大的值，而不是SM预测。特别是，$ r_ {d^*} $偏离实验测量的偏差变得较小，这对于Belle II实验的测量结果将来可能会很有趣。
We investigate the semi-leptonic decays of $\bar B \to D^{(*)} \ell\barν$ in terms of the Heavy-Quark-Effective-Theory (HQET) parameterization for the form factors, which is described with the heavy quark expansion up to $\mathcal O(1/m_c^2)$ beyond the simple approximation considered in the original CLN parameterization. An analysis with this setup was first given in the literature, and then we extend it to the comprehensive analyses including (i) simultaneous fit of $|V_{cb}|$ and the HQET parameters to available experimental full distribution data and theory constraints, and (ii) New Physics (NP) contributions of the $V_2$ and $T$ types to the decay distributions and rates. For this purpose, we perform Bayesian fit analyses by using Stan program, a state-of-the-art public platform for statistical computation. Then, we show that our $|V_{cb}|$ fit results for the SM scenarios are close to the PDG combined average from the exclusive mode, and indicate significance of the angular distribution data. In turn, for the $\text{SM} + \text{NP}$ scenarios, our fit analyses find that non-zero NP contribution is favored at the best fit point for both $\text{SM} + V_2$ and $\text{SM} + T$ depending on the HQET parameterization model. A key feature is then realized in the $\bar B \to D^{(*)} τ\barν$ observables. Our fit result of the HQET parameters in the $\text{SM} (+T)$ produces a consistent value for $R_D$ while smaller for $R_{D^*}$, compared with the previous SM prediction in the HFLAV report. On the other hand, $\text{SM}+V_2$ points to smaller and larger values for $R_D$ and $R_{D^*}$ than the SM predictions. In particular, the $R_{D^*}$ deviation from the experimental measurement becomes smaller, which could be interesting for future improvement on measurements at the Belle II experiment.
