Equation of State of Gluon Plasma from Gribov Region
  We describe the gluon plasma in zeroth order as a gas of free quasi-particles with a temperature-independent dispersion relation of Gribov type, $E(k) = \sqrt{k^2 + {M^4 \over k^2}}$, that results from the restriction of the physical state space to the Gribov region. The effective mass ${M^2 \over k}$ controls infrared divergences of finite-temperature perturbation theory. The equation of state of this gas is calculated and compared with numerical lattice data. At high temperature $T$ there are power corrections to the Stefan-Boltzmann law that are of relative order $1/T^3$ for pressure and $1/T^4$ for energy. 
Daniel Zwanziger