QCD Approach to B →Dπ Decays and CP Violation |
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作者姓名: | SU Fang ;WU Yue-Liang ;YANG Ya-Dong ;ZHUANG Ci |
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作者单位: | [1]Kavli Institute for Theoretical Physics China. Institute of Theoretical Physics, the Chinese Academy of Sciences (KITPC/ITP-CAS), Beijing 100080, China [2]Graduate School of the Chinese Academy of Sciences, Beijing 100039, China [3]Institute of Particle Physics, Huazhong Normal University, Wuhan 430079, China |
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基金项目: | The project supported in part by National Natural Science Foundation of China (NSFC) under Grant Nos. 10475105, 10491306, and 10675039 and the Knowledge Innovation Program (PKIP) of the Chinese Academy of Sciences |
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摘 要: | The branching ratios and CP violations of the B →Dπ decays, including both the color-allowed and the color-suppressed modes, are investigated in detail within QCD framework by considering all diagrams that lead to three effective currents of two quarks. An intrinsic mass scale as a dynamical gluon mass is introduced to treat the infrared divergence caused by the soft collinear approximation in the endpoint regions, and the Cutkosky rule is adopted to deal with a physical-region singularity of the on mass-shell quark propagators. When the dynamical gluon mass μg is regarded as a universal sca/e, it is extracted to be around μg = 440 MeV from one of the well-measured B →Dπ decay modes. The resulting predictions for all branching ratios are in agreement with the current experimental measurements. As these decays have no penguin contributions, there are no direct CP asymmetries. Due to interference between the Cabibbo-suppressed and the Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the B →D^±π^±↓ decays to be consistent with the experimental data at 1-σ level. More precise measurements will be helpful to extracting weak angle 2β+γ.
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关 键 词: | 量子动力学 衰变 核物理 胶子 |
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