Radiative Corrections for the Gauged Thirring Model in Causal   Perturbation Theory
  We evaluate the one-loop fermion self-energy for the gauged Thirring model in (2+1) dimensions, with one massive fermion flavor, in the framework of the causal perturbation theory. In contrast to QED$_3$, the corresponding two-point function turns out to be infrared finite on the mass shell. Then, by means of a Ward identity, we derive the on-shell vertex correction and discuss the role played by causality for nonrenormalizable theories. 
L. A. Manzoni, B. M. Pimentel and J. L. Tomazelli