The study of lepton flavor universality violation (LFUV) in semitauonic $b$-hadron decays has become increasingly important in light of long-standing anomalies in their measured branching fractions, and the large datasets anticipated from the LHC experiments and Belle II. In this review, a comprehensive survey of the experimental environments and methodologies for semitauonic LFUV measurements at the $B$ factories and LHCb is undertaken, along with an overview of the theoretical foundations and predictions for a wide range of semileptonic decay observables. The future prospects of controlling systematic uncertainties down to the percent level, matching the precision of standard model (SM) predictions, are examined. Furthermore, new perspectives and caveats on combinations of the LFUV data are discussed and the world averages for the $\mathcal{R}(D^{(*)})$ ratios are revisited. Here it is demonstrated that different treatments for the correlations of uncertainties from $D^{**}$ excited states can vary the current $3\sigma$ tension with the SM within a $1\sigma$ range. Prior experimental overestimates of $D^{**}\tau \nu$ contributions may further exacerbate this. The precision of future measurements is also estimated; their power to exploit full differential information, and solutions to the inherent difficulties in self-consistent new physics interpretations of LFUV observables, are explored.

中文翻译：

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Semitauonicb-强子衰变：轻子风味普遍性实验室

semitauonic中轻子风味普遍性违反（LFUV）的研究$b$鉴于其测量的分支分数的长期异常以及 LHC 实验和 Belle II 预期的大型数据集，强子衰变变得越来越重要。在这篇综述中，对半自动 LFUV 测量的实验环境和方法进行了全面调查。$乙$进行了工厂和 LHCb，同时概述了广泛的半轻子衰变可观测物的理论基础和预测。将系统不确定性控制到百分比水平，与标准模型 (SM) 预测的精度相匹配的未来前景进行了检查。此外，还讨论了关于 LFUV 数据组合的新观点和注意事项，以及世界平均水平$\mathcal{R}(D^{(*)})$重新审视比率。这里证明了对不确定性相关性的不同处理$D^{**}$激发态可以改变电流$3\sigma$与 SM 内的紧张关系$1\sigma$范围。先前的实验高估$D^{**}\tau \nu$捐款可能会进一步加剧这种情况。还估计了未来测量的精度；探索了他们利用完整差分信息的能力，以及对 LFUV 可观测物的自洽新物理解释中固有困难的解决方案。