REPULSIVE CORE OF NN S-WAVE SCATTERING IN A QUARK-MODEL WITH A CONDENSED VACUUM

We work in a chiral invariant quack model, with a condensed vacuum, ch aracterized by only one parameter. Bound state equations for the nucle on and Delta are solved in order to obtain an updated value of their r adii and masses. Nucleon-nucleon S-wave scattering is studied in the r esonating group method framework both for isospin T=1 and T=0. The pha se shifts are calculated and an equivalent local potential, which is c onsistent with K-N scattering, is derived. The result is a reasonable microscopic short range repulsion in the nucleon-nucleon interaction.