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 ΛQCD for the non-radiative matrix elements $$ \left\langle {M}_1{M}_2\left|{Q}_i\right|\overline{B}\right\rangle $$ M 1 M 2 Q i B ¯ of the current-current operators from the effective weak interactions. The rates of the branching fractions for the infrared-finite observables $$ \overline{B}\to {M}_1{M}_2\left(\gamma \right) $$ B ¯ → M 1 M 2 γ with photons of maximal energy ∆E ≪ ΛQCD 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.

We discuss the generalization of the leading-twist light-cone distribution amplitude for light mesons including QED effects. This generalization was introduced to describe virtual collinear photon exchanges at the strong-interaction scale ΛQCD in the factorization of QED effects in non-leptonic B-meson decays. In this paper we study the renormalization group evolution of this non-perturbative function. For charged mesons, in particular, this exhibits qualitative differences with respect to the well-known scale evolution in QCD only, especially regarding the endpoint-behaviour. We analytically solve the evolution equation to first order in the electromagnetic coupling αem, which resums large logarithms in QCD on top of a fixed-order expansion in αem. We further provide numerical estimates for QED corrections to Gegenbauer coefficients as well as inverse moments relevant to (QED-generalized) factorization theorems for hard exclusive processes.

We revisit the decay Λ 0 b → Λ + c −ν (= e, µ, τ) with a subsequent two-body decay Λ + c → Λ 0 π + in the Standard Model and in generic New Physics models. The decay's joint four-differential angular distribution can be expressed in terms of ten angular observables, assuming negligible polarization of the initial Λ b state. We present compact analytical results for all angular observables, which enables us to discuss their possible New Physics reach. We find that the decay at hand probes more and complementary independent combinations of Wilson coefficients compared to its mesonic counter parts B → D (*) −ν. Our result for the angular distribution disagrees with some of the results on scalar-vector interference terms in the literature. We provide numerical estimates for all angular observables based on lattice QCD results for the Λ b → Λ c form factors and account for a recent measurement of the parity-violating parameter in Λ + c → Λ 0 π + decays by BESIII. A numerical implementation of our results is made publicly available as part of the EOS software.