Phase diagrams in higher dimensional U(1) lattice gauge theory

In five or more dimensions, U(1) lattice gauge theory shows a strong first- order phase transition and metastable states in the region of the transitio n. Monte Carlo calculations carried out in dimensions up to seven illustrat e this behavior. These metastable states are well reproduced by gauge-fixed mean-field theory for the "superheated state" (beta < beta(c)) and by Pade approximants to the strong-coupling expansion for the "supercooled state" (beta > beta(c)) In analogy to a Van der Waal's system, a cubic equation of state is employed to connect the two metastable states in both the Monte C arlo and analytic calculations. A Maxwell construct is developed allowing f or the identification of the transition point and a complete, analytic desc ription of the phase diagram in five and higher dimensions.