2013/12/31 by Robert Dickinson, Jeff Forshaw, Peter Millington +1 · 1 citation
Physics and Astronomy · #Amplitude #Causality (physics) #Detector #Field (mathematics) #Field theory (psychology) #Quantum #Quantum Electrodynamics and Casimir Effect #Quantum Mechanics and Non-Hermitian Physics #Quantum and Classical Electrodynamics #Quantum field theory #Scattering amplitude #hep-ph #hep-th
paper · pdf · doi:10.1007/jhep06(2014)049
published as JHEP06(2014)049 · 24 pages; 6 figures; version accepted for publication in JHEP
openalex publication_date 2014/06/01 · arxiv created 2014/06/16 · arxiv updated 2014/06/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We introduce a way to compute scattering amplitudes in quantum field theory including the effects of particle production and detection. Our amplitudes are manifestly causal, by which we mean that the source and detector are always linked by a connected chain of retarded propagators. We show how these amplitudes can be derived from a path integral, using the Schwinger-Keldysh “in-in” formalism. Focussing on ϕ 3 theory, we confirm that our approach agrees with the standard S-matrix approach in the case of positive energy plane-wave scattering.