2024/12/08 by Shuangyi Li, Li, Shuang-Yi, Jie Xu +8 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Particle Detector Development and Performance #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2412.05989
openalex publication_date 2024/12/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Inspired by the newly reported B→ D^*(→ Dπ)ℓν_ℓ differential decay rates by the Belle and Belle II Collaborations, we revisit the Vcb puzzle in semi-leptonic B→ 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 Vcb 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 Vcb. We show that higher-order effects cannot eliminate the deviation between the exclusive and inclusive determinations of Vcb. Finally, utilizing the best-fit results obtained in the HQET parameterization as inputs, we predict the relevant observables, i.e., RD^*, FLD^*, and PτD^*, sensitive to new physics in the B→ D^*ℓν_ℓ decays. We conclude that lepton-universality violations still exist in the b→ cτν transitions.