Working directly with probabilities in quantum field theory

[摘要] 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.

[发布机构] Consortium for Fundamental Physics, School of Physics and Astronomy, University of Manchester, Manchester; M13 9PL, United Kingdom^1;School of Physics and Astronomy, University of Nottingham, Nottingham; NG7 2RD, United Kingdom^2

[效力级别] 力学 [学科分类] 力学，机械学

[关键词] Expectation values;Field operators;Light signalling;Matrix elements;On potentials;Quantum field theory;Transition probabilities