QCD factorization for exclusive non-leptonic B-meson decays: general arguments and the case of heavy-light final states

We provide a rigorous basis for factorization for a large class of non-lept onic two-body B-meson decays in the heavy-quark limit. The resulting factor ization formula incorporates elements of the naive factorization approach a nd the hard-scattering approach, but allows us to compute systematically ra diative ("non-factorizable") corrections to naive factorization for decays such as B --> D pi and B --> pi pi. We first discuss the factorization form ula from a general point of view. We then consider factorization for decays into heavy-light final states (such as B --> D pi) in more detail, includi ng a proof of the factorization formula at two-loop order. Explicit results for the leading QCD corrections to factorization are presented and compare d to existing measurements of branching fractions and final-state interacti on phases. (C) 2000 Elsevier Science B.V. All rights reserved.