论文标题
分支率的难题的可能解决方案，$ b \ toππ$损坏的$ cp $违反了扰动QCD方法
Possible solution of the puzzle for the branching ratio and $CP$ violation in $B\to ππ$ decays with a modified perturbative QCD approach
论文作者
论文摘要
我们使用修改的扰动QCD方法研究$ b \toπ$衰减。分支比率和$ cp $违规的情况是用所考虑的部分的横向动量计算的。包括与每个介子相关的Sudakov因子，以抑制QCD中的软贡献。使用$ b $梅森在QCD启发的相对论潜在模型中获得的波函数，抑制Sudakov因子对软贡献的抑制不够有效。必须引入$bπ$过渡的软尺度截止和软性颜色。包括顶点校正，夸克环和磁企鹅的主要临近领域贡献。为了解决$ b \toππ$衰减中的长期难题，这是$ b^0 \与π^0π^0 $的分支比的理论预测，比实验数据非常小，颜色octet矩阵元素是长距离动力学的。随着参数具有合理的值，所有分支比率和$ cp $违规都与实验数据一致。
We study $B\to ππ$ decay with a modified perturbative QCD approach. The branching ratios and $CP$ violation are calculated with the transverse momenta of partons considered. Sudakov factor associated with each meson is included to suppress soft contribution in QCD. With the wave function of $B$ meson obtained in QCD-inspired relativistic potential model being used, the suppression of Sudakov factor to the soft contribution is not effective enough. Soft scale cutoff and soft form factors of $Bπ$ transition and $ππ$ production have to be introduced. The main next-to-leading-order contributions of vertex correction, the quark-loop and magnetic penguin are included. To solve the long-standing puzzle in $B\toππ$ decay, that is the theoretical prediction of the branching ratio of $B^0\to π^0π^0$ being seriously smaller than experimental data, color-octet matrix element which is of long-distance dynamics is introduced. With parameters taken with reasonable values, all the branching ratios and $CP$ violation are well consistent with experimental data.
