Expectation values and vacuum currents of quantum fields

Abstract

Theory of expectation values is presented as an alternative to S-matrix theory for quantum fields. This change of emphasis is conditioned by a transition from the accelerator physics to astrophysics and cosmology. The issues discussed are the time-loop formalism, the Schwinger-Keldysh diagrams, the effective action, the vacuum currents, and the effect of particle creation. © 2008 Springer-Verlag Berlin Heidelberg.