Abstract
An exact representation of the causal QED fermion Green’s function, in an arbritrary external electromagnetic field, derived in Fried, Gabellini, and McKellar, and which naturally allows for nonperturbative approximations, is here used to calculate nonperturbative 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.
- Received 17 October 2002
DOI:https://doi.org/10.1103/PhysRevD.67.033004
©2003 American Physical Society