Singularity-softening prescription for the Bethe-Salpeter equation
  The reduction of the two fermion Bethe-Salpeter equation in the framework of light-front dynamics is studied for one gauge A+=0. The arising effective interaction can be perturbatively expanded in powers of the coupling constant g, allowing a defined number of gauge boson exchanges. The singularity of the kernel of the integral equation at vanishs plus momentum of the gauge is canceled exactly in on approuch. We studied the problem using a singularity-softening prescription for the light-front gauge. 
J.H.O.Sales and A.T.Suzuki