Non factorizable Effetcs in $B\to {\chi }_{c0}{K}^{-}$ from Charmed Meson Rescattering

The $B^{-}\to {\chi }_{c0}{K}^{-}$ decay which has no visible factorizable amplitude, could be induced by the Cabibbo-allowed, color-favored $B^{-} \to D_{s}D^{0}$,$B^{-} \to D^{0}{s}D^{0}$and$B \to D{s}^{}D^{}$ via the rescattering of these charmed mesons to ${\chi }_{co}{K}^{-}$. In this talk I would like to discuss a recent calculation \cite{Colangelo} of these effects for $B^{-}\to {\chi }_{c0}{K}^{-}$ and $B^{-}\to J\mathrm{/}\psi K^{-}$ decays. We find that charmed scattering effects seem capable of producing a large $B^{-} \to \chi_{c0} K^{-}$ branching ratio measured by the Babar and Belle Collaboration and make a significant contribution to the $B^{-}\to J\mathrm{/}\psi K^{-}$ branching ratios in agreement with experiments.