Regge Amplitudes and Final State Phases in the Decays B to D Pi
  The scattering amplitude of D Pi at the energy of the B mass can be calculated using Regge theory. Recent papers have used this to calculate the final state strong phases in the decays B to D Pi. It is argued that while the Regge amplitude can yield an absorption correction to the decay rate, it is not useful for determining the strong phase. 
Lincoln Wolfenstein