Another proof of Gell-Mann and Low's theorem
arXiv:math-ph/0612030 · doi:10.1063/1.2740469
Abstract
The theorem by Gell-Mann and Low is a cornerstone in QFT and zero-temperature many-body theory. The standard proof is based on Dyson's time-ordered expansion of the propagator; a proof based on exact identities for the time-propagator is here given.
5 pages