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CP asymmetry from hadronic charm rescattering in B± → π−π+π± decays at the high mass region
Physics Letters B ( IF 4.4 ) Pub Date : 2020-07-01 , DOI: 10.1016/j.physletb.2020.135490
I. Bediaga , T. Frederico , P.C. Magalhães

Abstract A model for the B ± → π − π + π ± decay amplitude is proposed to study the large CP violation observed at the high mass region of the Dalitz plane. A short distance b → u amplitude with the weak phase γ is considered together with the contribution of a hadronic charm loop and a s-wave D D ¯ → π π rescattering. In the model, the χ c 0 appears as a narrow resonant state of the D D ¯ system below threshold. It is introduced in an unitary two channel S-matrix model of the coupled D D ¯ and ππ channels, where the χ c 0 complex pole in D D ¯ channel shows its signature in the off-diagonal matrix element and in the associated D D ¯ → π π transition amplitude. The strong phase of the resulting decay amplitude has a sharp sign change at the D D ¯ threshold, changing the sign of the CP asymmetry, as it is observed in the data. We conclude that the hadronic charm loop and rescattering mechanism are relevant to the broadening of the CP asymmetry around the χ c 0 resonance in the ππ channel. This novel mechanism provides a possible interpretation for the CP asymmetry challenging experimental result presented by the LHCb collaboration for the B ± → π − π + π ± decay in the high mass region.

中文翻译:

来自强子魅力在 B± → π−π+π± 中重新散射的 CP 不对称性在高质量区域衰减

摘要 提出了一个 B ± → π − π + π ± 衰减幅度模型来研究在 Dalitz 平面的高质量区域观察到的大 CP 破坏。具有弱相位 γ 的短距离 b → u 振幅与强子魅力环和 s 波 DD ¯ → π π 再散射的贡献一起考虑。在模型中,χ c 0 表现为低于阈值的 DD 系统的窄共振态。它被引入耦合 DD ¯ 和 ππ 通道的酉双通道 S 矩阵模型中,其中 DD ¯ 通道中的 χ c 0 复极点在非对角矩阵元素和相关联的 DD ¯ → π 中显示其特征π 跃迁幅度。产生的衰减幅度的强相位在 DD 阈值处有一个急剧的符号变化,改变了 CP 不对称的符号,正如在数据中观察到的那样。我们得出结论,强子魅力环和再散射机制与 ππ 通道中 χ c 0 共振周围 CP 不对称性的扩大有关。这种新颖的机制为 LHCb 合作提出的 CP 不对称性具有挑战性的实验结果提供了可能的解释,用于高质量区域中的 B ± → π − π + π ± 衰变。
更新日期:2020-07-01
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