Study of pure annihilation decays B _d,s → D ⁰ D̄ ⁰

Abstract

Within the heavy quark limit and the hierarchy approximation λQCD mD mB, we analyze the B → D 0 D 0 and Bs → D 0 D 0 decays, which occur purely via annihilation type diagrams. As a rough estimate, we calculate their branching ratios and CP asymmetries in the perturbative QCD (PQCD) approach. The branching ratio of B → D 0 D 0 is about 3.8 × 10 −5 that is just below the latest experimental upper limit. The branching ratio of Bs → D 0 D 0 is about 6.8 × 10 −4 , which could be measured in LHC-b. From the calculation, it is found that this branching ratio is not sensitive to the weak phase angle γ. In these two decay modes, there exist CP asymmetries because of the interference between weak and strong interaction. However, these asymmetries are too small to be measured easily.