FINITE-SIZE EFFECTS AT PHASE-TRANSITION IN COMPACT U(1) GAUGE-THEORY

We present and discuss the results of a Monte-Carlo simulation of the phase transition in pure compact U(1) lattice gauge theory with Wilson action on a hypercubic lattice with periodic boundary conditions. The statistics are large enough to make a thorough analysis of the size d ependence of the gap. In particular we find a non-zero latent heat in the infinite volume limit. We also find that the critical exponents nu and alpha are consistent with the hyperscaling relation but confirm t hat the critical behavior is different from a conventional first-order transition.