MULTIPLICITY AND TRANSVERSE ENERGY-DISTRIBUTIONS ASSOCIATED TO RARE EVENTS IN NUCLEUS-NUCLEUS COLLISIONS

We show that in high energy nucleus-nucleus collisions the transverse energy or multiplicity distribution P-C, associated to the production of a rare, unabsorbed event C, is universally related to the standard or minimum bias distribution P by the equation P-C(nu) = nu/(nu)P[nu], with Sigma P(nu) = 1 and nu = E-T or n. Deviations from this formula are discussed, in particular having in view the formation of the plasm a of quarks and gluons. This possibility can be distinguished from abs orption or interaction of comovers, looking at the curvature of the J/ psi over Drell-Yan pairs as a function of E-T. (C) 1997 Elsevier Scien ce B.V.