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Probabilities and signalling in quantum field theory

Dickinson, Robert; Forshaw, Jeff; Millington, Peter

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Robert Dickinson

Jeff Forshaw

Peter Millington


We present an approach to computing probabilities in quantum field theory for a wide class of source-detector models. The approach works directly with probabilities and not with squared matrix elements, and the resulting probabilities can be written in terms of expectation values of nested commutators and anti-commutators. We present results that help in the evaluation of these, including an expression for the vacuum expectation values of general nestings of commutators and anti-commutators in scalar field theory. This approach allows one to see clearly how faster-than-light signalling is prevented, because it leads to a diagrammatic expansion in which the retarded propagator plays a prominent role. We illustrate the formalism using the simple case of the much-studied Fermi two-atom problem.

Journal Article Type Article
Acceptance Date Feb 24, 2016
Publication Date Mar 25, 2016
Deposit Date Jul 28, 2016
Publicly Available Date Jul 28, 2016
Journal Physical Review D
Print ISSN 2470-0010
Electronic ISSN 2470-0010
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 93
Issue 6
Article Number 065054
Public URL
Publisher URL


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