Calculation of pure annihilation type decay $B^+ \to D_s^+ \phi$

Abstract.

The rare decay $B^+ \to D_s^+ \phi$ can occur only via annihilation-type diagrams in the standard model. We calculated this decay in the perturbative QCD approach with Sudakov resummation. We found that the branching ratio of $B^+ \to D_s^+ \phi$ is of order $10^{-7}$; this may be measured in the near future by the KEK and SLAC B factories. The small branching ratio predicted in the standard model makes this channel sensitive to new physics contributions.