Strong phases and factorization for color suppressed decays

We prove a factorization theorem in QCD for the color suppressed decays [Formula Presented] and [Formula Presented] where M is a light meson. Both the color-suppressed and W-exchange or annihilation amplitudes contribute at lowest order in [Formula Presented] where [Formula Presented] 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 [Formula Presented] and [Formula Presented] rates and the equality of nonperturbative strong phases between isospin amplitudes, [Formula Presented] Relations between amplitudes and phases for [Formula Presented] are also derived. These results do not follow from large [Formula Presented] factorization with heavy quark symmetry.