Nonperturbative charming penguin contributions to isospin asymmetries in radiative B decays

Recent experimental data on the radiative decays B→Vγ, where V is a light vector meson, find small isospin violation in B→K*γ while isospin asymmetries in B→ργ are of order 20%, with large uncertainties. Using soft-collinear effective theory, we calculate isospin asymmetries in these radiative B decays up to O(1/mb), also including O(vαs) contributions from nonperturbative charming penguins (NPCP). In the absence of NPCP contributions, the theoretical predictions for the asymmetries are a few percent or less. Including the NPCP can significantly increase the isospin asymmetries for both B→Vγ modes. We also consider the effect of the NPCP on the branching ratio and CP asymmetries in B±→ V±γ.