Quarkonium suppression as a probe of a saturated gluon plasma?

Abstract

A dense parton system is expected to be formed in the early stage of relativistic heavy-ion collisions at RHIC energies and above. The probability of a quark gluon plasma production and the resulting strength of its signatures depends strongly on the initial conditions associated to the distributions of partons in the nuclear wave functions. At very high energies, the growth of parton distributions should saturate, possibly forming a Color Glass Condensate, which is characterized by a bulk momentum scale Q s . As a direct consequence, the possible signatures of the QGP should be Q s -dependent if the saturation scenario is valid for RHIC and LHC. In this Letter we assume the saturation scenario for the QGP formation and estimate the saturation scale dependence of quarkonium suppression. We conclude that, if this scenario is valid, the Υ suppression only occurs at large values of Q s .

QCD at high parton density

“…In Ref. [50] we have analyzed the quarkonium suppression as a probe of a saturated gluon plasma. In particular, we have estimated the quarkonium suppression and its dependence in the saturation scale at LHC energies.…”

“…In Ref. [50] we have obtained an expression for the screening mass in terms of the saturation scale, which is…”

“…The dependence of the screening mass in the saturation scale for two instants in the saturated plasma evolution. The long dashed curve characterize the dissociation screening mass for the meson Υ[50].…”

Parton percolation and J/ψ suppression

“…[2], assuming that a charmonium state i of scale Q i will be dissociated if it finds itself in a parton condensate of scale Q s ≥ Q i ; otherwise it will survive. This very simplistic picture allows an analysis of nuclear profile effects (condensed and non-condensed regions of the collision profile) and thus provides some direct predictions for the centrality-dependence of anomalous J/ψ suppression for given A and √ s. Other approaches that have been suggested include the study of the time evolution of the screening masses in the parton cascade [25] and in the color glass condensate [26].…”