Working directly with probabilities in quantum field theory

We present a novel approach to computing transition probabilities in quantum field theory, which allows them to be written directly in terms of expectation values of nested commutators and anti-commutators of field operators, rather than squared matrix elements. We show that this leads to a diagramm...

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Bibliographic Details
Main Authors: Dickinson, Robert, Forshaw, Jeff, Millington, Peter
Format: Article
Published: IOP Publishing 2017
Online Access:https://eprints.nottingham.ac.uk/47785/
Description
Summary:We present a novel approach to computing transition probabilities in quantum field theory, which allows them to be written directly in terms of expectation values of nested commutators and anti-commutators of field operators, rather than squared matrix elements. We show that this leads to a diagrammatic expansion in which the retarded propagator plays a dominant role. As a result, one is able to see clearly how faster-than-light signalling is prevented between sources and detectors. Finally, we comment on potential implications of this approach for dealing with infra-red divergences.