Heidelberg 1999 – scientific programme

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T: Teilchenphysik

T 306: Feldtheorie

T 306.2: Talk

Tuesday, March 16, 1999, 14:25–14:40, TE7

QED effective action at finite temperature — •Holger Gies — Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen

The QED effective Lagrangian in the presence of an arbitrary constant electromagnetic background field at finite temperature is derived in the imaginary-time formalism to one-loop order. The boundary conditions in imaginary-time reduce the set of gauge transformations of the background field, which allows for a further gauge invariant and puts restrictions on the choice of gauge. The additional invariant enters the effective action by a topological mechanism and can be identified with a chemical potential; it is furthermore related to Debye screening. In concordance with the real-time formalism, we do not find a thermal correction to Schwinger’s pair-production formula. The calculation is performed on a maximally Lorentz and gauge invariant stage.