Three-loop Hard Thermal Loop Free Energy for QED

Monday 17 Aug 2009, 14:00 → 15:00 Europe/Zurich

EPFL, Salle 727, BSP (Cubotron)

We calculate the free energy of a hot gas of electrons and photons to three loops using the hard-thermal-loop perturbation theory reorganization of finite temperature perturbation theory. We demonstrate that the hard-thermal-loop perturbation reorganization improves the convergence of successive approximations to the QED free energy at large coupling, e is about 2. The reorganization is gauge invariant by construction and formulated in Minkowski space-time. We obtain a completely analytic result for the resumed thermodynamic potential at three loops, which is in good agreement with that obtained from other methods, such as the Phi-derivable approach. The result sets the stage for the corresponding three-loop resumed calculation in QCD. Once obtained, this will represent the state-of-the-art calculation of the hightemperature QCD free energy. The talk is designed for general audiences with mostly plots explaining physical pictures, (almost) no technical details involved.