TRITON BINDING-ENERGY AND MINIMAL RELATIVITY

For relativistic three-body calculations, essentially two different ap proaches are in use: field theory and relativistic direct interactions . However, while results based upon relativistic field theory show an increase of the triton binding energy by about 0.3 MeV due to relativi stic effects, calculations that claim to apply relativistic direct int eractions obtain 0.3 MeV repulsion. In this paper, we discuss the orig in of such a discrepancy. We show that the use of an invariant two-bod y amplitude increases the triton binding energy by about 0.3 MeV, cons istent with the results from relativistic field theory. Furthermore, w e point out that in calculations relying on the direct-interactions ap proach, indeed p/m expansions are used, which may be a bad approximati on and the reason for the discrepancy.