Comparison of relativistic nucleon-nucleon interactions - art. no. 054002

We investigate the difference between those relativistic models based on in terpreting a realistic nucleon-nucleon interaction as a perturbation of the square of a relativistic mass operator and those models that use the metho d of Kamada and Glockle to construct an equivalent interaction to add to th e relativistic mass operator. Although both models reproduce the phase shif ts and binding energy of the corresponding nonrelativistic model, they are not scattering equivalent. The example of elastic electron-deuteron scatter ing in the one-photon-exchange approximation is used to study the sensitivi ty of three-body observables to these choices. Our conclusion is that the d ifferences in the predictions of the two models can be understood in terms of the different ways in which the relativistic and nonrelativistic S matri ces are related. We argue that the mass squared method is consistent with c onventional procedures used to fit the Lorentz-invariant cross section as a function of the laboratory energy.