The Three Loop Equation of State of QED at High Temperature
  We present the three loop contribution (order $e^4$) to the pressure of massless quantum electrodynamics at nonzero temperature. The calculation is performed within the imaginary time formalism. Dimensional regularization is used to handle the usual, intermediate stage, ultraviolet and infrared singularities, and also to prevent overcounting of diagrams during resummation. 
Claudio Coriano` (Argonne) and Rajesh Parwani (Saclay)