$V_{cb}$ puzzle in semi-leptonic $B\to D^*$ decays revisited
| Autor: | Li, Shuang-Yi, Xu, Jie, Shi, Rui-Xiang, Geng, Li-Sheng, Zhang, Yu-Jie, Zhang, Yi |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | Inspired by the newly reported $B\to D^*(\to D\pi)\ell\bar{\nu}_\ell$ differential decay rates by the Belle and Belle II Collaborations, we revisit the $V_{cb}$ puzzle in semi-leptonic $B\to D^*$ decays, considering the latest lattice QCD simulations and light-cone sum rule results. We examine the commonly used Caprini-Lellouch-Neubert (CLN), Boyd-Grinstein-Lebed (BGL), and heavy quark effective theory (HQET) parameterizations. We show that these three parameterizations lead to consistent results and reconfirm the $V_{cb}$ puzzle. Then, we use a state-of-the-art Bayesian method to estimate the impact of higher-order terms beyond the present HQET expansion on the uncertainty of $V_{cb}$. We show that higher-order effects cannot eliminate the deviation between the exclusive and inclusive determinations of $V_{cb}$. Finally, utilizing the best-fit results obtained in the HQET parameterization as inputs, we predict the relevant observables, i.e., $R_{D^*}$, $F_L^{D^*}$, and $P_\tau^{D^*}$, sensitive to new physics in the $B\to D^*\ell\bar{\nu}_\ell$ decays. We conclude that lepton-universality violations still exist in the $b\to c\tau\nu$ transitions. Comment: 21 pages, 1 figures, 9 tables |
| Databáze: | arXiv |
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