Irreversibility in quantum field theory
arXiv:quant-ph/9501004
Abstract
It is shown how the programme of decoherence can be applied in the context of quantum field theory. To illustrate the role of gauge invariance, we first discuss the charge superselection rule in quantum electrodynamics in some detail. We then present an example where macroscopic electromagnetic fields are ``measured" through interaction with charges and thereby rendered classical.
7 pages, LATEX, Contribution to the Clausthal-Symposium (August 1994)