RELATIVISTIC DELTA-OMEGA MEAN-FIELD THEORY FOR HYPERONS FROM A QUARK-MODEL

We suggest a phenomenological description of hypernuclear sigma-omega Dirac mean-field theory, where the meson-baryon vertices are based on the quark model with relativistic corrections. While the model is shown to be in agreement with the sigma-omega model for regular nuclei, large tensor omega-YY couplings are derived for omega-hyperon vertices. This coupling, which is negligible for nucleons, is capable of resolving the problem of the small spin-orbit interaction in AND hypernuclei within the Dirac approach, as was recently shown independently by Jennings. Our model explains the available data. It can also be the basis for more systematic theoretical studies. Predictions are thus presented for SIGMA and XI hypernuclei. Further improvements of the model are discussed.