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arXiv 1111.5000hep-ph
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单Cabibbo抑制D衰变中直接CP破坏的大小

Size of direct CP violation in singly Cabibbo-suppressed D decays

Joachim Brod, Alexander L. Kagan, Jure Zupan

摘要:

最近,LHCb合作研究了D -> K+ K-和D -> pi+ pi-时间积分CP不对称性之间的差异,提出了粲夸克衰变中直接CP破坏的第一个实验证据。我们估计了在标准模型中可以预期的效应的大小,并发现在1/mc的领先顺序下,它们小了一个数量级。然而,树级湮灭型振幅是已知的大实验。这意味着某些形式上1/mc抑制的企鹅振幅可以合理地解释LHCb测量。同时,这些振幅的味道破坏部分可以解释D -> K+ K-和D -> pi+ pi-衰减速率之间的巨大差异。

英文摘要:

The first experimental evidence for direct CP violation in charm-quark decays has recently been presented by the LHCb collaboration in the difference between the D -> K+ K- and D -> pi+ pi- time-integrated CP asymmetries. We estimate the size of the effects that can be expected within the Standard Model and find that at leading order in 1/mc they are an order of magnitude smaller. However, tree-level annihilation type amplitudes are known to be large experimentally. This implies that certain formally 1/mc-suppressed penguin amplitudes could plausibly account for the LHCb measurement. Simultaneously, the flavor-breaking parts of these amplitudes could explain the large difference between the D -> K+ K- and D -> pi+ pi- decay rates.

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