The study of backward-forward and forward-forward correlations in coll
isions of two nuclei at high energies allow us to distinguish between
the fusion of strings produced in the collision into new strings of hi
gher color and the possibility of the fusion of produced hadrons into
clusters. The results for AB collisions at the CERN Super Proton Synch
rotron (SPS) and the Brookhaven Relativistic Heavy Ion Collider (RHIC)
are discussed.