Thermodynamics of chromomagnetism

The thermodynamics of a system of gluons interacting with a constant color magnetic field is investigated. There is a first-order phase transition from a magnetic state at low temperature to a non-magnetic state at high temperature. The transition temperature corresponds closely to the critical temperatures obtained in a perturbative expansion, in the finite temperature dilute instanton gas approximation, and in the MIT bag model. The free energy of a heavy quark-antiquark pair increases linearly with distance below the transition temperature but decreases coulombically above it.