PHASE-STRUCTURE OF COMPACT LATTICE QED(3) WITH MASSLESS FERMIONS

In the framework of (2 + 1)-dimensional compact lattice QED with light fermions, we investigate the phase diagram in the (beta, N) plane. The approximations involved are related to an expansion of the effective fermionic action as a power series of the flavor number N. We also develop a new mechanism for understanding the N-critical phenomenon in the full theory. Our results for the specific heat show the existence of a first order phase transition Line at large-N, terminating in a critical point at finite beta. We give strong evidences that this qualitative result should not be changed with the inclusion of higher order terms in the N expansion.