The rare $\bar{B}^0_{d} \to \phi\gamma$ decays in the standard model and as a probe of R-parity violation

Abstract.

We present a first study of the rare annihilation decay $\bar{B}^0_d \to \phi\gamma$ in the standard model. Using the QCD factorization formalism, we find ${\cal B}(\bar{B}^0_d \to\phi\gamma ) = 3.6\times 10^{-12}$. The smallness of the decay rate in the standard model makes the decay a sensitive probe of new physics contributions. As an example, we calculate the effects of R-parity violating couplings. Within the available upper bounds for $\smash{\vert\lambda^{"}_{i23}\lambda^{"*}_{i12}\vert}$ and $\smash{\vert\lambda^{'}_{i32}\lambda^{'*}_{i12}\vert}$, $\smash{{\cal B}(\bar{B}^0_d \to\phi\gamma )}$ could be enhanced to the order of $10^{-9}\sim 10^{-8}$, which might be accessible at LHCB, B-TeV and the planned super high luminosity B factories at KEK and SLAC.