Acad Sinica, Inst High Energy Phys, Beijing 100039, Peoples R China
; CCAST, World Lab, Beijing 100080, Peoples R China
; Acad Sinica, Inst Theoret Phys, Beijing 100080, Peoples R China
Spin-orbit force of the NN interaction is studied in the framework of the chiral SU(3) quark model. Both symmetric and antisymmetric spin-orbit (LS) forces of the one gluon exchange and scalar meson exchanges are taken into account. It is shown that although the inclusions of the LS forces caused by the scalar meson exchanges and the antisymmetric LS terms in this model can notably strengthen the LS couplings in the states of P-3(J) of the NN interaction, an additional enhancement factor is still needed in order to describe the experimental data.