Renormalization and Chiral Symmetry Breaking in Quenched QED in   Arbitrary Covariant Gauge
  We extend a previous Landau-gauge study of subtractive renormalization of the fermion propagator Dyson-Schwinger equation (DSE) in strong-coupling, quenched QED_4 to arbitrary covariant gauges. We use the fermion-photon proper vertex proposed by Curtis and Pennington with an additional correction term included to compensate for the small gauge-dependence induced by the ultraviolet regulator. We discuss the chiral limit and the onset of dynamical chiral symmetry breaking in the presence of nonperturbative renormalization. We extract the critical coupling in several different gauges and find evidence of a small residual gauge-dependence in this quantity. 
Frederick T. Hawes (SCRI/Florida State University), Anthony G.   Williams (University of Adelaide, Australia), Craig D. Robe...