A study of pentaquark Theta state in the chiral SU(3) quark model

The structure of the pentaquark state uudd-sbar is studied in the chiral SU(3) quark model as well as in the extended chiral SU(3) quark model, in which the vector meson exchanges are included. Four configurations of JP=1/2- and four of JP=1/2+ are considered. The results show that the isospin T=0 state is always the lowest one for both JP=1/2- and JP=1/2+ cases in various models. But the theoretical value of the lowest one is still about 200-300 MeV higher than the experimental mass of $\Theta$. It seems that a dynamical calculation should be done for the further study.