THE PHASE-STRUCTURE OF QED3 WITH FERMION SELF-COUPLING

The ground state phase structure of QED3 with four-Fermi interactions and N flavors is determined via the 1/N Schwinger-Dyson equations. We consider two different four-Fermi couplings G and H, which can induce the breakdown of Z2 and parity symmetries, respectively. A critical surface in coupling constant space is determined, which delineates regions where dynamical breakdown of parity invariance as well as the discrete Z2 symmetry occurs from those in which these symmetries are preserved. We obtain a critical value of N, N(c) = N(c)(H), below which chiral symmetry breaking develops even for G = 0. As H approaches its critical line, new dynamical degrees of freedom arise which disfavor Z2 breakdown, thus lowering the value of N(c).