In-medium properties of Θ in symmetric nuclear matter

The properties of nuclear matter is carefully analysed in relativistic mean-field formalism(RMF), it is found that the non-linear self-interaction of σ meson affects the properties strongly at high density and there is also strong parameter dependence in this region. We introduce a density dependent scalar coupling according to the idea of QMC model, find that its effect to properties of nuclear matter is little at low density, however, the effect at high density is obviously. The Θ+ (as an structureless particle) effective masses in medium is studied, M Θ+ ≃ 0.67MΘ+=1030 MeV at normal nuclear density. The density dependent scalar coupling obviously affects the baryon effective masses in nuclear matter, especially at high density. We review the kaon meson in medium and find the RMF model considered density dependent coupling is consistent with ChPT model in a certain extent. We develop another method to describe the Θ+ in RMF, find the effective mass M Θ+ ≃ 0.73MΘ+=1120 MeV much larger than the usual RMF prediction; the potential depth of Θ+ in nuclear matter with the new method is UΘ+ ≃-37.5 MeV much shallower than UΘ+ ≃-90 MeV predicted with the usual RMF. PACS: 21.65+f, 21.30.Fe