Correlated nucleons in nuclei

Jefferson Laboratory data (K. Egiyan et. al., talk given at the April 2004 meeting of the American Physical Society) indicate that there exist short-range correlations in nucleons bound in nuclei leading to a step-like behavior of the heavy-to-light nuclei cross section ratios versus the Bjorken-x in deeply inelastic scattering (DIS). A possible theoretical model to interprete this effect is the formation of multi-quark clusters in the nucleus. These are due to the overlap of nucleon wavefucntions leading to six, nine, or more valence quark color singlets. A semiclassical algorithm has been developed to calculate the multi-quark-cluster probabilities for arbitrarily large nuclei. Two-body correlations are introduced and the results are compared to those obtained with the independent particle model. The calculated probabilities are close to those needed to fit the DIS data as well as data on Drell-Yan production and J/$\Psi$ suppression in nucleon-nucleus collisions.