论文标题
$ b^\ pm \ toρ^0π^\ pm $和$ b^\ pm \ toσπ^\ pm衰减中的cp违规
CP Violation in $B^\pm\to ρ^0π^\pm$ and $B^\pm\to σπ^\pm$ Decays
论文作者
论文摘要
LHCB使用$ S $ - 波组件的三种不同方法分析了Dalitz图中$ B^+\ toπ^+π^-π^+$的衰减幅度。发现具有$σ$（或$ f_0（500）$）的模式在ISOBAR模型中表现出15 \％的CP不对称性，而$ f_2（1270）$模式的模式为40 \％\％不对称。相反，在所有三种方法中，发现主要的准二体衰变$ b^ - toρ^0π^ - $的CP不对称与零一致，而所有现有的理论预测都会导致$ -7 \％\％$ $ $ $ -45 \ $ -45 \％\％$ $ $ $。我们表明，在QCD分解（QCDF）的框架中，可以理解$ B^ - \toρ^0π^ - $中几乎消失的CP违规行为。它来自$ 1/m_b $的功率校正，这是由于企鹅歼灭而引起的企鹅振幅以及由于硬旁观者的互动而引起的颜色抑制的树幅度。企鹅歼灭和硬观众的交互对$ a_ {cp}（b^ - \toρ^0π^ - ）$造成贡献，以使其与零一致。在QCDF中研究了$ b^ - \toσ/f_0（500）π^ - $中的分支分数和CP不对称性，结果与实验一致。
The decay amplitude of $B^+\to π^+π^-π^+$ in the Dalitz plot has been analyzed by the LHCb using three different approaches for the $S$-wave component. It was found that the mode with $σ$ (or $f_0(500)$) exhibited a CP asymmetry of 15\% in the isobar model, whereas the $f_2(1270)$ mode had a 40\% asymmetry. On the contrary, CP asymmetry for the dominant quasi-two-body decay $B^-\toρ^0π^-$ was found to be consistent with zero in all three approaches, while all the existing theoretical predictions lead to a negative CP asymmetry ranging from $-7\%$ to $-45\%$. We show that the nearly vanishing CP violation in $B^-\toρ^0π^-$ is understandable in the framework of QCD factorization (QCDF). It arises from the $1/m_b$ power corrections to the penguin amplitudes due to penguin annihilations and to the color-suppressed tree amplitude due to hard spectator interactions. Penguin annihilation and hard spectator interactions contribute destructively to $A_{CP}(B^-\toρ^0π^-)$ to render it consistent with zero. The branching fraction and CP asymmetry in $B^-\toσ/f_0(500)π^-$ are investigated in QCDF with results in agreement with experiment.
