QCD Factorization in B → πK, ππ Decays and Extraction of Wolfenstein Parameters

In the heavy-quark limit, the hadronic matrix elements entering nonleptonic B-meson decays into two light mesons can be calculated from first principles including “nonfactorizable ” strong-interaction corrections. The B → πK,ππ decay amplitudes are computed including electroweak penguin contributions, SU(3) violation in the light-cone distribution amplitudes, and an estimate of power corrections from chirally-enhanced terms and annihilation graphs. The results are then used to reduce the theoretical uncertainties in determinations of the weak phases γ and α. In that way, new constraints in the (¯ρ, ¯η) plane are derived. Predictions for the B → πK, ππ branching ratios and CP asymmetries are also presented. A good global fit to the (in part preliminary) experimental data on the branching fractions The study of nonleptonic two-body decays of B mesons is of primary importance for the exploration of CP violation and the determination of the flavour parameters of the Standard Model. Because of the interference of several competing amplitudes, these