Effect of D-D̄ mixing on the measurement of γ in B→DK decays

D-D̄ mixing is the source of the largest theoretical uncertainty in the extraction of γ from B→DK decays. In the standard model, the mixing can have a rate close to its current experimental upper bound and is CP conserving to an excellent approximation. We show that neglecting CP-conserving D-D̄ mixing leads to an error in the determination of γ only at second order in the small parameters ΔmD/ΓD and ΔΓD/ ΓD and is therefore very small and can be safely neglected.