TY - JOUR

T1 - Probabilities and signalling in quantum field theory

AU - Dickinson, R

AU - Forshaw, J

AU - Millington, P

PY - 2016/3/25

Y1 - 2016/3/25

N2 - 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.

AB - 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.

UR - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=pure_starter&SrcAuth=WosAPI&KeyUT=WOS:000372723300008&DestLinkType=FullRecord&DestApp=WOS

U2 - 10.1103/PhysRevD.93.065054

DO - 10.1103/PhysRevD.93.065054

M3 - Article

SN - 1550-7998

VL - 93

SP - 1

EP - 12

JO - Physical Review D (Particles, Fields, Gravitation and Cosmology)

JF - Physical Review D (Particles, Fields, Gravitation and Cosmology)

IS - 6

M1 - 065054

ER -