Two Body B Decays, Factorization and LambdaQCD/mb Corrections

By using the recent experimental measurements of B -> pi pi and B -> K pi branching ratios, we find that the amplitudes computed at the leading order of the LambdaQCD/mb expansion disagree with the observed BRs, even taking into account the uncertainties of the input parameters. Beyond the leading order, Charming and GIM penguins allow to reconcile the theoretical predictions with the data. Because of these large effects, we conclude, however, that it is not possible, with the present theoretical and experimental accuracy, to determine the CP violation angle gamma from these decays. We compare our results with those obtained with the parametrization of the chirally enhanced non-perturbative contributions by BBNS. We also predict large asymmetries for several of the particle--antiparticle BRs, in particular BR(B+ -> K+ pi0), BR(Bd -> K+ pi-) and BR(Bd -> pi+ pi-).