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The \(B \rightarrow {{D}^{(*)}} {l}{\nu _l}\) decays in the pQCD approach with the Lattice QCD input

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  • Physics & Astronomy
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Science Bulletin

Abstract

In this paper, we studied the semileptonic decays \(B \rightarrow D^{(*)} l^- \bar{\nu }_l\) 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 \(0\le q^2 \le m_\tau ^2\) and the lattice QCD input at the endpoint \(q^2=q^2_{\mathrm{max}}\). We then calculated the ratios R(D) and \(R(D^*)\) of the branching ratios \({\mathcal{B}}(B \rightarrow D^{(*)} l^- {\bar{\nu }}_l)\) and found numerically that (1) the “pQCD + Lattice QCD” predictions for the branching ratios \({\mathcal{B}}(B \rightarrow D^{(*)} l^-{\bar{\nu}}_l)\) 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.

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Notes

  1. This is the figure appeared in Z. Ligeti’s talk given at the ICTP summer school on particle physics, June 15–26, 2015, Trieste, Italy; and where the HQET predictions for \(R(D^{(*)})\) the relevant experimental measurements from BaBar, Belle and LHCb collaborations, and the world averages have been illustrated explicitly.

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Acknowledgments

We wish to thank Hsiang-nan Li and Wen-Fei Wang for valuable discussions. This work was supported by the National Natural Science Foundation of China (11235005, 11105115 and 11505148) and by the key project of Henan’s Universities (15A140033).

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Authors and Affiliations

  1. College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang, 464000, China

    Ying-Ying Fan, Ru-Min Wang & Bing-Zhong Li

  2. Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing, 210023, China

    Zhen-Jun Xiao

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  1. Ying-Ying Fan
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Correspondence to Zhen-Jun Xiao.

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Fan, YY., Xiao, ZJ., Wang, RM. et al. The \(B \rightarrow {{D}^{(*)}} {l}{\nu _l}\) decays in the pQCD approach with the Lattice QCD input. Sci. Bull. 60, 2009–2015 (2015). https://doi.org/10.1007/s11434-015-0959-9

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  • DOI: https://doi.org/10.1007/s11434-015-0959-9

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