Abstract
Dong, Munczek, and Roberts have shown how the full 3-point vertex that appears in the Schwinger-Dyson equation for the fermion propagator can be expressed in terms of a constrained function in massless quenched QED. However, this analysis involved two key assumptions: that the fermion anomalous dimension vanishes in the Landau gauge and that the transverse vertex has a simplified dependence on momenta. Here we remove these assumptions and find the general form for a new constrained function that ensures the multiplicative renormalizability of the fermion propagator nonperturbatively. We then study the restriction imposed on by recent perturbative calculations of the vertex and compute its leading logarithmic expansion. Since should reduce to this expansion in the weak coupling regime, this should serve as a guide to its nonperturbative construction. We comment on the perturbative realization of the constraints on
- Received 24 July 1997
DOI:https://doi.org/10.1103/PhysRevD.57.1242
©1998 American Physical Society