Electroweak effects in the extraction of the CKM angle γ from B → Dπ decays

The angle γ of the standard CKM unitarity triangle can be determined from tree-level B  -meson decays essentially without hadronic uncertainties. We calculate the second-order electroweak corrections for the B→DπB→Dπ modes and show that their impact on the determination of γ could be enhanced by an accidental cancellation of poorly known hadronic matrix elements. However, we do not expect the resulting shift in γ   to exceed |δγDπ/γ|≲O(10−4)|δγDπ/γ|≲O(10−4).