Study of the Hyperon-Nucleon Interaction in the Quark Model

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The purpose of this project is to study the hyperon-nucleon interaction in the constituent quark model. We have succeeded in a unified description of the hyperon-nucleon (YN) and nucleon-uncleon (NN) interaction in the RGM formulation of the SU_6 quark model, in which the full Fermi-Breit interaction with explicit flavor symmetry breaking is incorporated with minimum effective meson-exchange potentials induced from the scalar-meson central and pi, K tensor components of the Nijmegen model-F potential. With few strength parameters determined from the deuteron binding energy and NN ^1S_0 phase shift, all the low-energy cross sections of the YN interaction currently available are reasonably reproduced. In the intermediate-energy region with P_<Lab>=400-600MeV/c, we have found that this model yields a couple of new features in the total cross sections of the SIGMA^+p and LAMBDAp scatterings, which are not observed in the standard phenomenological one-boson-exchange potentials like the Nijmegen potentials. Namely, in SIGMA^+p system the big bump due to the very attractive ^1P_1 phase shifts observed in the Nijmegen models do not show up in the quark model. In LAMBDAp total scattering cross sections, our quark model yields a broad peak with the magnitude of about 100 mb, which is due to the very strong LS^< (-) > force predicted in the quark model. These differences are related to the basic characteristics of the quark model and the meson-exchange potentials in the short-range region, and are subject to the experimental test in near future.