Critical behavior in pure compact U(1) gauge theory on toroidal lattices

We report results of a high-statistics Monte Carlo simulation of the phase transition in compact U(1) lattice gauge theory with Wilson action on a hypercubic lattice with periodic boundary conditions. By a careful analysis of the histograms of the plaquette energy distribution, we can measure gaps with sufficient accuracy on lattice sizes ranging from 44 to 164. We find that all data points can be successfully reproduced by the two-parameter ansatz Δe(L) = Δe(∞) + aL with a non-zero latent heat in the infinite volume limit. On the other hand we confirm that the pseudo-critical temperatures scale with a critical exponent ν = 0.326(8) different from the first-order prediction ν = 0.25. We also check the scaling of the maximum of the specific heat with a critical exponent α consistent with the hyperscaling relation.