Phenomenological study of quarkonium suppression and the impact of the energy gap between singlets and octets

Jean-Paul Blaizot,Miguel Ángel Escobedo

doi:10.1103/physrevd.104.054034

Abstract

The study of heavy quarkonium suppression in heavy-ion collisions represents an important source of information about the properties of the quark-gluon plasma produced in such collisions. In a previous paper, we have considered how to model the evolution of a quarkonium in such a way that the solution of the resulting equations evolves toward the correct thermal equilibrium distribution for a homogeneous and static medium. We found that it is crucial to take into account the energy gap between singlet and octet configurations when the temperature is not much greater than this energy gap. In this paper, we explore in more detail the phenomenological consequences of this observation in the more realistic situation of an expanding system. We consider two different scenarios, based on the same approximation scheme, but on different choices of parameters. In the first case, we rely on a Hard Thermal Loop approximation, while the second case is based on a recent determination of the static potential in lattice QCD. In both cases, we compute the decay width and the nuclear modification factor, both taking the energy gap into account and ignoring it. We find that the impact on the predictions is as large in the expanding medium as it is in the static case. Our conclusion is that this energy gap should be taken into account in phenomenological studies.

Highlights

Several physical phenomena are commonly invoked to explain the production of quarkonia in ultra-relativistic heavy-ion collisions that are presently intensively studied at the LHC [1,2,3]
II, we review the model that we developed in [21] and we discuss the imaginary part of the potential and its energy dependence
We have explored the phenomenological consequences of the observations made in [21], where we highlighted the importance of taking into account the energy gap between singlet and octet states when computing the decay width of a quarkonium bound state in a medium

Summary

Introduction

Several physical phenomena are commonly invoked to explain the production of quarkonia in ultra-relativistic heavy-ion collisions that are presently intensively studied at the LHC [1,2,3]. Aside from the initial suggestion of the color screening of the binding potential by the quark-gluon plasma [4], collisions between the plasma constituents and the quarkonia could lead to a suppression of the production rate. In the effective theory picture where the interactions of quarkonia with the plasma are dominated by color dipolar interactions, collisions induce singlet to octet transitions [7].

Objectives

Findings

Discussion

Conclusion