Extended-soft-core NN potentials in momentum space. II. Meson-pair exchange potentials

The partial wave projection of the Nijmegen soft-core potential model for meson-pair-exchange (MPE) for NN scattering in momentum space is presented. Here, nucleon-nucleon momentum-space MPE potentials are NN interactions where either one or both nucleons contains a meson-pair vertex. Dynamically, the meson-pair vertices can be viewed as describing in an effective way (part of) the effects of heavy-meson exchange and meson-nucleon resonances. From the point of view of “duality,” these two kinds of contribution are roughly equivalent. Part of the MPE vertices can be found in the chiral-invariant phenomenological Lagrangians that have a basis in spontaneous broken chiral symmetry. It is shown that the MPE interactions are a very important component of the nuclear force, which indeed enables a very successful description of the low and medium energy NN data. Here we present a precise fit to the NN data with the extended-soft-core model containing one-boson-exchange, PS-PS-, and MPE potentials. An excellent description of the NN data for T_Lab<~350MeV is presented and discussed. Phase shifts are given and a χ_pdp²=1.15 is reached.