Study of Pure Annihilation Decays B_{d,s} \to D^{0} \bar D^{0}

TL;DR

This paper analyzes pure annihilation decays of B mesons into D0 and anti-D0 using perturbative QCD, estimating branching ratios and CP asymmetries, with implications for experimental detection and CP violation studies.

Contribution

It provides the first perturbative QCD estimates of branching ratios and CP asymmetries for these pure annihilation decay modes of B mesons.

Findings

Branching ratio of B→D0D0 is about 3.8×10^{-5}.

Branching ratio of Bs→D0D0 is about 6.8×10^{-4}.

CP asymmetries are small and challenging to measure.

Abstract

With heavy quark limit and hierarchy approximation $\lambda_{QCD}\ll m_D\ll m_B$, we analyze the $B\to D^0\bar D^0$ and $B_s\to D^0\bar D^0$ decays, which occur purely via annihilation type diagrams. As a roughly estimation, we calculate their branching ratios and CP asymmetries in Perturbative QCD approach. The branching ratio of $B\to D^0\bar D^0$ is about $3.8\times10^{-5}$ that is just below the latest experimental upper limit. The branching ratio of $B_s\to D^0\bar D^0$ is about $6.8\times10^{-4}$, which could be measured in LHC-b. From the calculation, it could be found that this branching ratio is not sensitive to the weak phase angle $\gamma$. In these two decay modes, there exist CP asymmetries because of interference between weak and strong interaction. However, these asymmetries are too small to be measured easily.