Nuclear dependence coefficient alpha(A,q(Tau)) for Drell-Yan and J/psi production - art. no. 054008

Define the nuclear dependence coefficient alpha(A,q(T)) in terms of the rat io of the transverse momentum spectrum in hadron-nucleus and in hadron-nucl eon collisions d sigma(hA)/dq(T)(2)/d sigma(hN)/dq(T)(2)=A(alpha(A,qT)). We argue that, in the small q(T) region, the alpha(A,q(T)) for the Drell-Yan and J/psi production is given by a universal function a+bq(T)(2), where the parameters a and b are completely determined by either calculable quantiti es or independently measurable physical observables. We demonstrate that th is universal function alpha(A,q(T)) is insensitive to A for normal nuclear targets. For a color deconfined nuclear medium, alpha(A,q(T)) becomes stron gly dependent on A. We also show that our alpha(A,q(T)) for the Drell-Yan p rocess is naturally linked to the perturbatively calculated alpha(A,q(T)) a t large q(T) without any foe parameters, and alpha(A,q(T)) is consistent wi th E772 data for all q(T).