Nucleon nucleon interaction in a chiral constituent quark model

We study the nucleon-nucleon interaction within a chiral constituent quark model where the hyperfine interaction is due to pseudoscalar meson exchange. We calculate the S-3(1) and S-1(0) phase shifts by using the resonating group method. Their behaviour clearly indicates the presence of a strong repulsive core at short distance. This is due to the spin-flavour symmetry of the interaction and to the quark interchange between the two interacting nucleons. We add a sigma-meson exchange quark-quark interaction which provides a medium range attraction necessary to describe the S-1(0) phase shift. We also explore the role of a tensor interaction at the quark level.