N N scattering phase shifts in a chiral constituent quark model

We study the nucleon-nucleon interaction within a chiral constituent quark
model which reproduces succesfully the baryon spectra. We calculate the $^3S_1$
and $^1S_0$ phase shifts by using the resonating group method. They clearly
indicate the presence of a strong repulsive interaction at short distance,
due to the spin-flavour symmetry of the quark-quark interaction and of the
quark interchange between the two interacting nucleons. A $\sigma$-meson
exchange
quark-quark interaction, providing a medium-range attraction, helps to get
closer to the experimental phase shifts.