In-medium Properties of ${\Theta }^{+}$ as a K$\pi$N structure in Relativistic Mean Field Theory

Abstract

The properties of nuclear matter are discussed with the relativistic mean-field theory (RMF).Then, we use two models in studying the in-medium properties of ${\Theta }^{+}$: one is the point-like ${\Theta }^{\ast }$ in the usual RMF and the other is a K$\pi$N structure for the pentaquark. It is found that the in-medium properties of ${\Theta }^{+}$ are dramatically modified by its internal structure. The effective mass of ${\Theta }^{+}$ in medium is, at normal nuclear density, about 1030 MeV in the point-like model, while it is about 1120 MeV in the model of K$\pi$N pentaquark. The nuclear potential depth of ${\Theta }^{+}$ in the K$\pi$N model is approximately -37.5 MeV, much shallower than -90 MeV in the usual point-like RMF model.

8 pages, 5 figures