Effective action for the order parameter of the deconfinement transition   of Yang-Mills theories
  The effective action for the Polyakov loop serving as an order parameter for deconfinement is obtained in one-loop approximation to second order in a derivative expansion. The calculation is performed in $d\geq 4$ dimensions, mostly referring to the gauge group SU(2). The resulting effective action is only capable of describing a deconfinement phase transition for $d>d_{\text{cr}}\simeq 7.42$. Since, particularly in $d=4$, the system is strongly governed by infrared effects, it is demonstrated that an additional infrared scale such as an effective gluon mass can change the physical properties of the system drastically, leading to a model with a deconfinement phase transition. 
Holger Gies (Tubingen U.)