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

The structure of the pentaquark state uudd (s) over bar, 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. The lowest four configurations of J(pi) = 1 and four of J(pi) = 1/2(+) for the 5 quark cluster are considered. The results show that the isospin T = 0 state is always the lowest one for both J(pi) = 1/2(-) and J(pi) = 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 (C) 2004 Elsevier B.V. All rights reserved.