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Approximations to the QED Fermion Green's Function in a Constant External Field

S. K. J. Daniel, B. H. J. McKellar

hep-pharXiv:hep-ph/0210226

Abstract

An exact representation of the causal QED fermion Green's function, in an arbritrary external electromagnetic field, derived by Fried, Gabellini and McKellar, and which naturally allows for non-perturbative approximations, is here used to calculate non-perturbative approximations to the Green's function in the simple case of a constant external field. Schwinger's famous exact result is obtained as the limit as the order of the approximation approaches infinity.

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