Quarkonium binding and entropic force

Abstract

A $$Q{\bar{Q}}$$QQ¯ 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 $$Q{\bar{Q}}$$QQ¯ separation gives rise to a growing repulsion. We study the role of these phenomena for in-medium $$Q{\bar{Q}}$$QQ¯ binding and dissociation. It is found that the relevant potential for $$Q{\bar{Q}}$$QQ¯ binding is the free energy $$F$$F; with increasing $$Q{\bar{Q}}$$QQ¯ separation, further binding through the internal energy $$U$$U is compensated by repulsive entropic effects.