Dips in Partial Wave Amplitudes from Final State Interactions
  We consider the dip-peak structures in the J=0 partial wave amplitudes for processes $\gamma\gamma\rightarrow W^+W^-~ \mbox{and}~\gamma\gamma,gg\rightarrow t\overline{t}$ taking into account the corresponding Born term process and the rescattering process where the intermediate state is rescattered through the exchange of Higgs resonance state in the direct channel. 
Charles B. Chiu and Duane A. Dicus