CRITICAL BEHAVIOR IN (2+1)-DIMENSIONAL QED WITH A FOUR-FERMION INTERACTION

We analyze QED3 with a scalar-scalar type four-fermion interaction in the framework of 1/N expansion. We have derived the Dyson-Schwinger gap equation up to the next-to-leading order and determined the dynamically generated fermion mass as a function of the number of fermion flavors N and a scaled coupling θ. We observe that the critical behaviors are separated by the point [Formula: see text] and, contrary to the leading behaviors, there are mass generations even when θ ≥ θc with the critical flavor Nc. The critical line on the Nc−θc plane is presented. We also discuss the vacuum stability of our model, and confirm that our nontrivial solutions are energetically preferred to the perturbative solution Σ(p)=0.