String clustering and J/psi suppression in nuclear collisions

We study the clustering of colour strings in the transverse plane of nucleu s-nucleus collisions and argue that deconfinement sets in when the string d ensity within a cluster reaches a critical value. We show that this implies a minimal cluster size at the onset of deconfinement, which in turn result s in discontinuous behaviour for J/psi suppression. (C) 1998 Elsevier Scien ce B.V. All rights reserved.