INFLUENCE OF THE FULL VERTEX AND VACUUM POLARIZATION ON THE FERMION PROPAGATOR IN (2-DIMENSIONAL QED(1))

We investigate the influence of the full vacuum polarization and verte x function on the fermion propagator, using the coupled Dyson-Schwinge r equations for the photon and fermion propagator. We show that, withi n a range of vertex functions, the general behavior of the fermion pro pagator does not depend on the exact details of the vertex, both in th e massless and in the massive phase. Independent of the precise vertex function, there is a critical number of fermion flavors for dynamical mass generation in (2+1)-dimensional QED. A consistent treatment of t he vacuum polarization is essential for these results.