Branching ratio and CP violation of B →ππ decays in the perturbative QCD approach -: art. no. 074009

We calculate the branching ratios and CP asymmetries for B-o -->pi (+)pi (-), B+-->pi (+)pi (o), and B-o --> pi (o)pi (o) decays. in a perturbative QCD approach. In this approach, we calculate nonfactorizable and annihilation type contributions, in addition to the usual factorizable contributions. We find that the annihilation diagram contributions are not very small as previously argued. Our result is in agreement with the measured branching ratio of B --> pi (+)pi (-) by the CLEO Collaboration. With a non-negligible contribution from annihilation diagrams and a large strong phase, we predict a large direct CP asymmetry in B-o --> pi (+)pi (-), and pi (o)pi (o), which can be tested by the current running B factories.