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A quark meson coupling model based on SU(3)L × SU(3)R symmetry and scale invariance is proposed. The quarks and mesons get masses through symmetry broken. We apply this SU(2) chiral constituent quark model to investigating the nuclear matter at finite temperature and density. The effective baryon masses, compression modulus and hyperon potentials are all reasonable. The critical temperature of liquid-gas phase transition is also calculated in this model.

The purpose of this paper is to study the Λ-N interaction by using the meson exchange theory. We have considered four processes:l) Single K meson exchange, 2) Single η and single ω meson exchange, 3) Box diagrams of 2π and πρ exchanges with the intermediate states of ΣN, and 4) Box diagrams of 2π and πρ exchanges with the intermediate states of ΣΔ. For simplicity, the zero initial momentum approximation and the closure approximation have been taken in the calculation. The results are reasonable and consistent with experimental data. Especially for the cases of and , the theoretica1 spectra of and are in good agreement with experimental data.

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The equivalent one-boson-exchange potentials of the N-N, N-Δ and Δ-Δ interaction were calculated rigorously in momentum space with the vertex functions derived from quark-pair-creation model. The results of the N-N interaction were compared with those calculated approximately in coordinate space and the conventional one-boson-exchange potentials. All of the results indicate that they have very similar behaviour for the medium- and Long-range parts.