SU(3) symmetry breaking and CP violation in D -> PP decays
SU(3) symmetry breaking and CP violation in D -> PP decays
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DOI：
10.1103/physrevd.86.014014
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发表时间：
2012-05
影响因子：
5
通讯作者：
Hai-Yang Cheng;C. Chiang
中科院分区：
文献类型：
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作者：
Hai-Yang Cheng;C. Chiang
最近，LHCb和CDF合作组织发现了符咒领域CP违反的证据。采用拓扑图解的方法，研究了单cabibbo抑制的D→PP衰变弱衰变树幅值中flavor SU(3)对称性破缺效应。在允许颜色和抑制颜色的幅值中，对称性破缺是通过因式分析来估计的，而在w交换幅值中，对称性破缺是通过拟合相关分支分数数据来估计的。我们发现，相对于颜色允许的树振幅，w交换振幅保持在第二象限，尽管一种类型的w交换振幅有两种可能性。另一方面，在QCD分解的框架内对弱衰减企鹅振幅进行了评估。利用从cabibbo有利衰减模式中提取的拓扑树振幅输入和QCD企鹅振幅的微扰结果，我们对单cabibbo抑制模式的分支分数和CP不对称性进行了预测。分支分数的预测一般是在SU(3)极限的基础上改进的。我们得出结论，对于w交换振幅的两个解，d0→K + K−和d0→π + π−的直接CP不对称性分别约为−(0.139±0.004)%和−(0.151±0.004)%。我们还发现d0→k0 k0的CP不对称性主要受w交换幅值在- 0.62 × 10−3到- 1.82 × 10−3之间的干扰。我们研究了两种新的物理情景的现象学含义，以解释在粲扇区中观测到的CP不对称，一种具有大企鹅振幅，另一种具有大色磁偶极子算子。我们发现这两种情况可以通过测量一组衰减模式的CP不对称性来区分。
Evidence of CP violation in the charm sector has been observed recently by the LHCb and CDF Collaborations. Adopting the topological diagram approach, we study flavor SU(3) symmetry breaking effects in the weak decay tree amplitudes of singly Cabibbo-suppressed D → PP decays. The symmetry breaking in the color-allowed and color-suppressed amplitudes is estimated with the help of the factorization ansatz, while that in the W-exchange amplitude is done by fitting to related branching fraction data. We find that the W-exchange amplitudes stay in the second quadrant relative to the color-allowed tree amplitude, albeit there are two possibilities for one type of Wexchange amplitude. The weak decay penguin amplitudes, on the other hand, are evaluated within the framework of QCD factorization. Using the input of topological tree amplitudes extracted from the Cabibbo-favored decay modes and the perturbative results for QCD penguin amplitudes, we make predictions for the branching fractions and CP asymmetries of singly Cabibbo-suppressed modes. The predictions of branching fractions are generally improved from those in the SU(3) limit. We conclude that the direct CP asymmetry difference between D 0 → K + K − and D 0 → π + π − is about −(0.139 ± 0.004)% and −(0.151 ± 0.004)% for the two solutions of W-exchange amplitudes, respectively. We also find that the CP asymmetry of D 0 → K 0 K 0 dominated by the interference between W-exchange amplitudes ranges from −0.62 × 10 −3 to −1.82 × 10 −3 . We study phenomenological implications of two new physics scenarios for explaining the observed CP asymmetry in the charm sector, one with large penguin amplitudes and the other with a large chromomagnetic dipole operator. We find that the two scenarios can be discriminated by the measurements of CP asymmetries of a set of decay modes.