Off-shell behavior of the scattering amplitude and the structure of NN potentials

We perform calculations and comparative analysis of the off-shell scattering matrices and related pp --> ppgamma reaction observables for various types of N N potentials-with forbidden states and with short-range repulsion. The emphasis is on studying the effects of the shape and depth of the central part of forbidden-state potentials on the behavior of the above quantities and on establishing the role of meson-exchange components in the N N interaction. We show that, when using potentials that give a good description of phase shifts and the proper behavior of the scattering matrix for low momentum transfers, the reaction pp --> ppgamma does not allow the choice between the potentials to be made, at least up to a proton energy of 400 MeV in the laboratory frame. (C) 2002 MAIK "Nauka/Interperiodica".