一种研究强子多体B衰变中CP不对称性的色散方法
A dispersive method to study CP asymmetries in hadronic multi-body $B$ decays
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中文总结 AI 辅助
该研究介绍一种基于低不变质量下成对强子末态相互作用普遍性构建强子多体B衰变振幅的色散方法，将振幅分源项和末态相互作用项，以低能ππ相互作用为例，成功预测低能区相关分布及不对称性，助于理解LHCb报道的CP不对称性，还表明非共振同位旋-2贡献起关键作用。
中文摘要 AI 辅助
我们详细介绍了一种基于低不变质量下成对强子末态相互作用的普遍性来构建强子多体B衰变振幅的色散方法。该方法能将振幅分为由唯象参数控制的源项和由两体动力学精确知识决定的末态相互作用项。以确定的低能ππ相互作用为例，用于理解在\(B^{\pm}\rightarrow K^{\pm}\pi^+\pi^-\)中观测到的增强的局域CP破坏。仅拟合角度积分CP不对称数据，该方法成功预测了低能区事件的Dalitz图微分分布和CP不对称性。这有助于更好理解LHCb最近报道的大的局域CP不对称性，表明其并非由CP破坏效应的绝对增强驱动，而是由几个分波相互作用导致的CP守恒部分的抑制引起。此外，我们表明广泛被忽视的非共振同位旋-2贡献在该系统CP破坏描述中起关键作用。该方法可直接应用于其他末态两强子相互作用驱动CP破坏的多体衰变。
英文摘要
We present the details of a dispersive method to construct the amplitudes for hadronic multibody $B$ decays based on the universality of pairwise hadronic final-state interactions at low invariant masses. This approach allows us to split the amplitude into source terms controlled by phenomenological parameters and final-state interactions, governed by the precise knowledge of two-body dynamics, both resonant and non-resonant. As a concrete application, we make use of the well-determined low-energy pion-pion ($ππ$) interactions to understand the enhanced localized CP violation observed in $B^{\pm}\rightarrow K^{\pm}π^+π^-$. Fitting only angle-integrated CP-asymmetry data, the method successfully predicts the Dalitz plot differential distribution of events and of the CP asymmetry in the low-energy region. This allows for a better understanding of the large localized CP asymmetry recently reported by LHCb, which is shown not to be driven by an absolute enhancement of CP-violating effects, but by a suppression of the CP-conserving part resulting from the interplay of several partial waves. Moreover, we show that the widely-neglected non-resonant isospin-2 contributions play an essential role in the description of CP violation in this system. The method can be straightforwardly adapted to other multibody decays, where final-state two-hadron interactions drive the CP violation.
