Infrared and light-cone limit in hot QED

Abstract

In hot gauge theories a breakdown of the hard thermal loop expansion occurs for light-like external momenta or in the infrared region. In QED where a resummation of ladder diagrams is usually advocated, it is shown that long range magnetic interations involve a broader set of graphs. The consequence is a generalized compensation of the hard modes damping terms at leading order in the infrared limit and near the light-cone. The relevance of the so-called improved hard thermal loop resummation scheme is discussed.