Antiparticle Contribution in the Cross Ladder Diagram for Bethe-Salpater   Equation in the Light-Front
  We construct the homogeneous integral equation for the vertex of the bound state in the light front with the kernel approximated to order g^4. We will truncate the hierarchical equations from Green functions to construct dynamical equations for the two boson bound state exchanging interacting intermediate bosons and including pair creation process contributing to the crossed ladder diagram. 
J.H.O. Sales and A.T. Suzuki