The Coulomb-Higgs phase transition in Z(8) and q=8 U(1)-Higgs models

Abstract

The Coulomb-Higgs phase transition of the four dimensional Z${}_8$ gauge model is studied. We find clear first order properties in contradiction with the previously stressed second order behavior. That transition point may be regarded as the end of a transition line of the U(1)-Higgs model with charge $q=8$, that has been also assumed of second order. We show that this line is first order in a wide region, with a decreasing latent heat that goes to zero when closing to the 4--$d$ XY model limit.

Comments: Document in postscript; 6 pages including 3 figures. Preprint FT/UCM/5/93