Quarkonium Binding and Entropic Force

TL;DR

This paper investigates how medium effects like color screening and entropy influence quarkonium binding and dissociation in a hot quark-gluon plasma, highlighting the importance of free energy as the relevant potential.

Contribution

It clarifies the roles of free energy, internal energy, and entropy in quarkonium binding within a hot medium, emphasizing the dominance of free energy for in-medium binding.

Findings

Free energy F is the relevant potential for Q-Qbar binding.

Entropy effects lead to repulsion that counteracts internal energy.

Binding is primarily governed by the free energy in the medium.

Abstract

A Q-Qbar bound state represents a balance between repulsive kinetic and attractive potential energy. In a hot quark-gluon plasma, the interaction potential experiences medium effects. Color screening modifies the attractive binding force between the quarks, while the increase of entropy with Q-Qbar separation gives rise to a growing repulsion. We study the role of these phenomena for in-medium Q-Qbar binding and dissociation. It is found that the relevant potential for Q-Qbar binding is the free energy F; with increasing Q-Qbar separation, further binding through the internal energy U is compensated by repulsive entropic effects.