Minimal QCDF Model for $B\to\pi K$ Puzzle

Abstract

In this work, we propose a model by combining the parameterization method and the QCD factorization to study the $B\to\pi K$ puzzle. The parameterization introduces twelve parameters, the weak angle $\gamma$ and the other eleven hadronic parameters. These hadronic parameters are calculated by the QCD factorization (QCDF). The calculational accuracy of the QCDF is improved by including the twist-3 three parton tree and one loop corrections. Three additional nonperturbative strong phases from the gluonic penguin, color suppressed, and color favored tree diagrams are required to account for the direct CP asymmetries. The weak angle, three nonperturbative strong phases, and four scale variables are assumed as fitting parameters. These eight parameters are determined by a least squares fit to the eight measurements. The fit shows that the hadronic parameters need to be process-dependent. The process-dependent hadronic parameters break the isospin symmetry `dynamically'. A large negative relative phase associated with the internal up quark gluonic penguin diagram is observed. The weak angle $\gamma$ is found to be $72.1\pm5.8$ degree, being consistent with the world averaged value, $72.1\pm5.8$ degree. By a least squares fit to the mixing induced asymmetry $S(\pi^{0}K_{S})=0.58\pm0.06$, the weak angle $\beta$ is determined to be $22.9\pm2.1$ degree, which is in a well agreement with the world averaged value, $22.5\pm4.4\pm0.6$ degree. The model predicts the ratio $C^{\prime}/T^{\prime}$ (color suppressed/color favored) to be $0.59\pm0.08$. The above evidences indicate that the model can solve the $B\to\pi K$ puzzle consistently.