Abstract

We study the recently discovered Theta(+) baryon in the context of the perturbative chiral quark model. The basic configuration of the (Theta(+) is a pentaquark bound state, where the single particle wave functions are the ground state solutions of a confining potential. We classify the resulting pentaquark multiplets as the J(P) = 1/2(-) and 3/2(-) flavor SU(3) antidecuplet. The full mass spectrum of the multiplets is determined by including the meson and gluon cloud contributions, which induce flavor SU(3) breaking. The resulting 3/2(-) antidecuplet is about 185 MeV heavier than the 1/2(-) one, mainly because of the semi-perturbative gluon effects. We assign the observed Theta(+) baryon as a member of the 1/2(-) antidecuplet and discuss in particular its relation to the recent experimental signal for a Xi(--) baryon.