$B^{-}\to K^{-}{\chi }_{c0}$ decay from charmed meson rescattering

We study the process $B^{-}\to K^{-}{\chi }_{c0}$ considering intermediate charmed meson rescattering effects. For this decay mode the naive factorization ansatz would predict a vanishing amplitude. We estimate contributions from the $D_s^{(\ast )}{D}^{(\ast )}\to K^{-}{\chi }_{c0}$ rescattering amplitudes, and compare the result with recent experimental measurements. We find that rescattering effects are able to produce a large branching ratio consistent with measurements by Belle Collaboration. We also consider rescattering effects in $B^- \to K^- J/\psi$, arguing that they play a similar role in producing a large branching fraction for this colour-suppressed decay mode.