Final State Interactions in $B -> D \rho$ and $B -> D^{*}\pi$ Decays
  We analyze final state strong interaction effects in $B -> D \rho$ and $B -> D^{*}\pi$ decays using the Regge model. We find that, due to the smallness of the contributions from the non-leading Regge trajectories ($\rho$, $f$, $\pi$ etc.), final state interaction phases are small if the Pomeron coupling to the charm quark is suppressed in comparison to lighter quarks. Our conclusion is that for $B$ decays into states containing charm, final state interaction effects should play a minor role. 
G. Nardulli and T. N. Pham