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arXiv 0711.3282hep-ph
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纯湮没衰变B_{d,s} \to D^{0} \bar D^{0}的研究

Study of Pure Annihilation Decays B_{d,s} \to D^{0} \bar D^{0}

Ying Li, Juan Hua

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13 pages, 4 figures
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摘要：

利用重夸克极限和等级近似$λ_{QCD}\ll m_D\ll m_B$，我们分析了$B\to D^0\bar D^0$和$B_s\to D^0\bar D^0$衰变，这两种衰变完全通过湮灭型图发生.作为粗略的估计，我们用微扰QCD方法计算了它们的分支比和CP不对称性。$B\to D^0\bar D^0$的分支比约为$3.8\times10^{-5}$，其刚好低于最新的实验上限。$B_s\to D^0\bar D^0$的支化比约为$6.8\times10^{-4}$，其可在LHC-b中测量。从计算中可以发现，该分支比对弱相位角$γ$不敏感。由于弱相互作用和强相互作用之间的相互作用，在这两种衰变模式中存在CP不对称性。然而，这些不对称性太小，难以测量。

英文摘要：

With heavy quark limit and hierarchy approximation $λ_{QCD}\ll m_D\ll m_B$, we analyze the $B\to D^0\bar D^0$ and $B_s\to D^0\bar D^0$ decays, which occur purely via annihilation type diagrams. As a roughly estimation, we calculate their branching ratios and CP asymmetries in Perturbative QCD approach. The branching ratio of $B\to D^0\bar D^0$ is about $3.8\times10^{-5}$ that is just below the latest experimental upper limit. The branching ratio of $B_s\to D^0\bar D^0$ is about $6.8\times10^{-4}$, which could be measured in LHC-b. From the calculation, it could be found that this branching ratio is not sensitive to the weak phase angle $γ$. In these two decay modes, there exist CP asymmetries because of interference between weak and strong interaction. However, these asymmetries are too small to be measured easily.

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