SOFT 2-PION-EXCHANGE NUCLEON NUCLEON POTENTIALS

Two-pion-exchange nucleon-nucleon potentials are derived for the pseudo-vector pion-nucleon interaction, assuming strong dynamical pair-suppression. At the pion-nucleon vertices we include Gaussian form factors, which are incorporated into the relativistic two-body framework by using a dispersion representation for the one-pion-exchange amplitude. The Fourier transformations are performed using a factorization technique for the energy denominators. This leads to analytic expressions for the TPE-potentials containing at most one-dimensional integrals. The TPE-potentials are calculted up to orders f{hook}4 and ( m M)f{hook}4. The terms of order f{hook}4 come from the adiabatic contributions of the parallel and crossed three-dimensional momentum-space TPE-diagrams, and from the non-adiabatic contributions of the OPE-iteration. The ( m M)-corrections are due to the 1 M-terms in the pion-nucleon vertices. The latter are typical for the PV-coupling and would be absent for the PS-coupling. The Gaussian form factors lead to soft TPE-potentials. These potentials can readily be exploited in NN-calculations in combination with, e.g., the Nijmegen soft-core OBE-model, and in nuclear (matter) calculations. © 1991.