Relativistic Studies of Few-Body Systems Using the Bethe–Salpeter Approach

The Bethe–Salpeter equation is one of the most appropriate tools in quantum field theory for the treatment of bound state systems. We review two problems in this approach: (i) the influence of the cross-ladder (non-planar) interaction kernel with color degrees of freedom in two-boson systems; and (ii) the higher Fock-state contributions to the three-boson bound state. Some new calculations have been performed to illustrate the previous topics.