Chiral quark model study of udss̄ tetraquark states

The energies of the low-lying isoscalar and isovector udss̄ configurations with spin-parity J^P = 0⁺, 1⁺, and 2⁺ are calculated in the chiral SU(3) quark model and the extended chiral SU(3) quark model by using the variational method. The model parameters are determined by the same method as in our previous work, and they still can satisfactorily describes the nucleon-nucleon scattering phase shifts and the hyperon-nucleon cross sections. The s-channel annihilation interaction is fixed by the masses of K and K* mesons, and the configuration mixing is considered. The results show that the udss̄ configuration with I = O and J^P = 1⁺ lies lower than the K*K* threshold, and furthermore, this state has a very small KK* component, thus it can be treated as a possible tetraquark candidate.