QED factorization of non-leptonic B decays

We show that the QCD factorization approach for B-meson decays to charmless hadronic two-body final states can be extended to include electromagnetic corrections. The presence of electrically charged final-state particles complicates the framework. Nevertheless, the factorization formula takes the same form as in QCD alone, with appropriate generalizations of the definitions of light-cone distribution amplitudes and form factors to include QED effects. More precisely, we factorize QED effects above the strong interaction scale Λ_QCD for the non-radiative matrix elements 〈 M₁M₂| Q_i| B¯ 〉 of the current-current operators from the effective weak interactions. The rates of the branching fractions for the infrared-finite observables B¯ → M₁M₂(γ) with photons of maximal energy ∆E ≪ Λ_QCD is then obtained by multiplying with the soft-photon exponentiation factors. We provide first estimates for the various electromagnetic corrections, and in particular quantify their impact on the πK ratios and sum rules that are often used as diagnostics of New Physics.