NN CORE INTERACTIONS AND DIFFERENTIAL CROSS-SECTIONS FROM ONE GLUON EXCHANGE

We derive nonstrange baryon-baryon scattering amplitudes in the nonrelativistic quark model using the ''quark Born diagram'' formalism. This approach describes the scattering as a single interaction, here the one-gluon-exchange (OGE) spin-spin term followed by constituent interchange, with external nonrelativistic baryon wave functions attached to the scattering diagrams to incorporate higher-twist wave-function effects. The short-range repulsive core in the NN interaction has previously been attributed to this spin-spin interaction in the literature; we find that these perturbative constituent-interchange diagrams do indeed predict repulsive interactions in all I, S channels of the nucleon-nucleon system, and we compare our results for the equivalent short-range potentials to the core potentials found by other authors using nonperturbative methods. We also apply our perturbative techniques to the NDELTA and DELTADELTA systems: Some DELTADELTA channels are found to have attractive core potentials and may accommodate ''molecular'' bound states near threshold. Finally we use our Born formalism to calculate the NN differential cross section, which we compare with experimental results for unpolarized proton-proton elastic scattering. We find that several familiar features of the experimental differential cross section are reproduced by our Born-order result.