Collision dissociation of heavy quarkonia in dense partonic systems

Abstract

The influence of collisions in a hot partonic medium on the formation of heavy quarkonia is investigated. We find that the initial color octet propagation of$Q\bar Q$ pairs created in nuclear collisions leads to a large cross section for collision dissociation even before Debye screening of the quarkonium potential in the color singlet final state becomes effective. This leads to a sizeable suppression of quarkonium states in addition to previously considered effects. The concept of a quarkonium “formation time”, during which the$Q\bar Q$ pair is not affected by the surrounding medium, is shown to be incorrect. In particular, we argue that the υ resonance will always be suppressed in nuclear collisions, contrary to recent suggestions that an unsuppressed υ state might signal quarkgluon plasma formation.