HOT GLUON MATTER IN A CONSTANT A0-BACKGROUND

We compute the effective action of finite T SU(3) gauge theory in a constant diagonal background field A0(t, x)=B03T3+B08T8 in the general covariant background gauge up to terms of order g3. B03,8 shield the infrared singularities and the aim is to study whether the minimum of the effective action would determine their values dynamically. We find that the order g2 term depends explicitly on the gauge fixing parameter ξ. Since the background field screens already at the tree diagram level the interactions of the six non-diagonal gluon fields they do not contribute to the plasmon-like g3 term. The two diagonal fields A03, A08 do, but the electric mass squared they develop will become negative if the background fields are larger than about T/g. Hence large background fields make the system unstable. © 1990 Springer-Verlag.