Phase structure of U(1) lattice gauge theory with a monopole term

Abstract

We investigate four-dimensional compact U(1) lattice gauge theory with a monopole term added to the Wilson action. First we consider the phase structure at negative \ensuremath{\beta}, revealing some properties of a third phase region, in particular the existence of a number of different states. Then our present studies concentrate on larger values of the monopole coupling \ensuremath{\lambda} where the confinement-Coulomb phase transition turns out to become of second order. Performing a finite-size analysis we find that the critical exponent \ensuremath{\nu} is close to but, however, different from the Gaussian value and that in the range considered \ensuremath{\nu} increases somewhat with \ensuremath{\lambda}.