Hyperon-Nucleon Interaction and Strangeness Production in PP Collisions

A new model for the hyperon-nucleon (ΛN, ΣN) interaction is presented. The model incorporates the standard one-boson exchange contributions of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) symmetry relations. As the main feature of the new model, the exchange of two correlated pions or kaons, both in the scalar-isoscalar (σ) and vector-isovector (ρ) channels, is included. Furthermore, results of a model calculation for the reactions pp → NΛK and pp → NΣK near their thresholds are reported. Special attention is paid to the cross section ratio σ<INF>pp→pΛK⁺</INF>/σ<INF>pp→pΣ⁰K⁺</INF> which was found to be unexpectedly large in recent experiments.