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arXiv 0908.2320hep-phhep-ex
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$B\to Kπ$衰变

$B\to Kπ$ decays

T. N. Pham

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摘要：

虽然QCD因式分解（QCDF）可以产生足够大的$B\to Kπ$分支比接近实验，预测的直接CP不对称性在${\bar B}^{0}\to K^{+}π^{-}$衰变然而仍然是相当低于实验，即使在湮灭项的大的负相，根据现有的计算。这表明在衰变振幅中存在一个额外的强相位，可能来自长距离末态相互作用（FSI），如迷人的企鹅。在本文中，我们表明，通过添加到$B\to Kπ$衰减QCDF振幅，实部和吸收部分的强度分别为企鹅振幅的10%和30%，我们可以使$B\to Kπ$分支比和${\bar B}^{0}\to K^{-}π^{+}$ CP不对称接近测量值。我们还发现，色允许的电弱企鹅是可感知的，从QCDF电弱-强企鹅干涉项和测量的$B^{-}\to {\bar K}^{0}π^{-}$，我们得到了$(9.0\pm 0.3)\times 10^{-6}$的${\bar B}^{0}\to {\bar K}^{0}π^{0}$分支比，比实验稍低。同样，根据${\bar B}^{0}\to K^{-}π^{+}$分支比预测的$B^{-}\to K^{-}π^{0}$值与实验结果吻合良好。这表明${\bar B}^{0}\to {\bar K}^{0}π^{0}$的测量值实际上应低于当前测量值。

英文摘要：

Though QCD Factorization(QCDF) could produce sufficiently large $B\to Kπ$ branching ratios close to experiments, the predicted direct CP asymmetry in ${\bar B}^{0}\to K^{+}π^{-}$ decay is however still quite below experiment, even with a large negative phase in the annihilation term, according to existing calculations. This suggests the presence of an additional strong phase in the decay amplitude which could come from the long-distance final state interactions(FSI) like charming penguin. In this paper, we show that, by adding to the $B\to Kπ$ decay QCDF amplitude, a real part and an absorptive part with a strength 10% and 30% of the penguin amplitude, respectively, we could bring the $B\to Kπ$ branching ratios and the ${\bar B}^{0}\to K^{-}π^{+}$ CP asymmetry close to the measured values. We also find that the color-allowed electroweak penguin is appreciable and that from the QCDF electroweak-strong penguin interference terms and the measured $B^{-}\to {\bar K}^{0}π^{-}$ we obtain $(9.0\pm 0.3)\times 10^{-6}$ for the ${\bar B}^{0}\to {\bar K}^{0}π^{0}$ branching ratio, a bit lower than experiment. Similarly, the predicted value for $B^{-}\to K^{-}π^{0}$ in terms of the ${\bar B}^{0}\to K^{-}π^{+}$ branching ratio agrees well with experiment. This suggests that the measured value for ${\bar B}^{0}\to {\bar K}^{0}π^{0}$ in fact should be lower than the current measured value.

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