Debye Screening in the QCD plasma

Various definitions for the QCD Debye mass and its evaluation are reviewed in a non-perturabtive framework for the study of screening of general static sources. While it is possible to perturbatively integrate over scales $\sim T$ and thus construct a 3d effective theory, the softer scales $\sim gT$ and $\sim g^2T$ are strongly coupled for temperatures $\lsim 10^7$ GeV and require lattice simulations. Within the effective theory, a lattice treatment of screening at finite quark densities $\mu \lsim 4/T$ is also possible.