Strong phases and factorization for color suppressed decays

We prove a factorization theorem in QCD for the color suppressed decays B-bar0→D0M0 and B-bar0→D*0M0 where M is a light meson. Both the color-suppressed and W-exchange or annihilation amplitudes contribute at lowest order in ΛQCD/Q where Q={mb,mc,Eπ}, so no power suppression of annihilation contributions is found. A new mechanism is given for generating nonperturbative strong phases in the factorization framework. Model-independent predictions that follow from our results include the equality of the B-bar0→D0M0 and B-bar0→D*0M0 rates and the equality of nonperturbative strong phases between isospin amplitudes, δ(DM)=δ(D*M). Relations between amplitudes and phases for M=π,ρ are also derived. These results do not follow from large Nc factorization with heavy quark symmetry