Abstract
The Schwinger-Dyson equation for the fermion propagator in quenched four-dimensional QED is solved using a nonperturbative ansatz for the fermion-photon vertex that satisfies the Ward-Takahashi identity, ensures the multiplicative renormalizability of the fermion equation, and reproduces low-order perturbation theory in the appropriate limit. The fermion propagator then possesses a chiral-symmetry-breaking phase only when the coupling is larger than a critical value . This critical coupling is almost exactly gauge independent as is the dynamically generated mass, in complete contrast to the popular rainbow approximation.
- Received 20 July 1993
DOI:https://doi.org/10.1103/PhysRevD.48.4933
©1993 American Physical Society