Iterated Resolvent Function for the Ladder Bethe-Salpeter Equation
  We developed the formal connection of the field theoretical Bethe-Salpeter equation including the ladder approximation with its representation on the light-front for a bosonic model. We use the light-front Green's function for the N-particle system for two-particles plus N-2 intermediate bosons. We derived an infinite set of coupled hierarchy equations or iterated resolvent from which the Green's function can be calculated. These equations allow a consistent truncation of the light-front Fock-space. We show explicitly the represention of the covariant two-body T-matrix and bound state vertex in the light-front. 
J.H.O. Sales, T.Frederico, B.M.Pimentel and B.V.Carlson