Lee-Yang Zeros and the Chiral Phase Transition in Compact Lattice QED

In this paper we present a detailed study of the phase structure in the \β -m plane for Compact Lattice QED. We analyse the scaling properties of the distribution of the partition function zeros in the complex fermion mass plane 4^4, 6^4, 8^4 and 10^4 lattices. The partition function is numerically evaluated by using two independent methods, based respectively on a standard HMC (Hybrid Monte Carlo) and on an alternative approach derived from the MFA (Microcanonical Fermionic Average). The finite size scaling behaviour gives strong indications for a first order phase transition at any value of the fermion mass. The reliability of the result follows from the remarkable agreement between the two independent methods.