The Rare Radiative Annihilation Decays $\bar{B}^0_{s,d} \to J/\psi\gamma$

We investigate the physics potential of the annihilation decays $\bar{B}^0_{s,d} \to J/\psi$ $\gamma$ in the Standard Model and beyond. In naive factorization approach, the branching ratios are estimated to be $\mathcal{B}(\bar{B}^0_s \to J/\psi\gamma)=1.40\times 10^{-6}$ and $\mathcal{B}(\bar{B}^0_d \to J/\psi\gamma)=5.29\times 10^{-8}$. In the framework of QCD factorization, we compute the non-factorizable corrections and get $\mathcal{B}(\bar{B}^0_s \to J/\psi\gamma) = 2.11\times10^{-7}$, $\mathcal{B}(\bar{B}^0_d \to J/\psi\gamma) =7.65\times10^{-9}$. Future measurements of these decays would be useful for testing the factorization frameworks. The smallness of these decays in the SM make them sensitive probes of New Physics. As an example, we will consider the possible admixture of (V+A) charge current to the standard (V-A) current. This admixture will give significant contributions to the decays.