The $B\to D^{()} l\nu_l$ decays in the pQCD approach with the Lattice QCD input

• Main Authors: Fan, Ying-Ying, Xiao, Zhen-Jun, Wang, Ru-Min, Li, Bing-Zhong
• Format: Journal Article
• Language: English
• Published: 26.05.2015
• Subjects: Physics - High Energy Physics - Experiment; Physics - High Energy Physics - Phenomenology
• DOI: 10.48550/arxiv.1505.07169

Science Bulletin Vol. 60 (2015) 2009-2015 In this paper, we studied the semileptonic decays $B \to D^{(*)} l^- \bar{\nu}_l$ by using the "pQCD+Lattice QCD" method. We made the extrapolation for the six relevant form factors by using the input values obtained from the pQCD factorization approach in the low $q^2$ region of $0\leq q^2 \leq m_\tau^2$, and the Lattice QCD input at the end-point $q^2=q^2_{\rm max}$. We then calculated the ratios $R(D)$ and $R(D^*)$ of the branching ratios ${\cal B}(B \to D^{(*)} l^- \bar{\nu}_l)$, and found numerically that (1) the "pQCD+Lattice QCD" predictions for the branching ratios ${\cal B}(B \to D^{(*)} l^-\bar{\nu}_l)$ agree well with the measured values within one standard deviation, and (2) the "pQCD+Lattice QCD" predictions for the ratios $R(D^{(*)})$ are $ R(D)=0.337^{+0.038}_{-0.037}$ and $ R(D^*)=0.269^{+0.021}_{-0.020}$, they agree with the data within $2\sigma$ deviation, in other words, one can explain the "$R(D^{(*)})$-puzzle" in the framework of the standard model.