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 is obtained without taking recourse to phenomenological models.