Light front field theory treatment of the 2N problem

The Weinberg equation, which is the exact formulation of the Bethe-Salpeter type equation in the light front field theory, considered according to the old fashioned perturbation rules, offers a unique opportunity to study relativistically the nature of the NN forces. We found that the binding energies of a few MeV, and the phase shifts for the lab. energies (0.1 - 0.3) GeV are quite sensitive to the forces at short distances, which are directly connected to the relativistic effects. Our results differ substantially, depending on the Lippmann-Schwinger and the Weinberg treatment. In a simple spinless model calculation this difference may be as large as (60 - 90)% of the deuteron binding energy. (orig./WL)