In the lattice U(1) gauge-Higgs model with radial degrees of freedom, a phase-transition point appears in the β=0 axis for small λ, independent of the charge q of the Higgs fields. Then, with relation to the model without radial degrees of freedom, new phases appear in the (β,J) phase diagram, whose location and order of corresponding phase transitions are studied by a Monte Carlo simulation. We also investigate the existence or nonexistence of free charge in all phases by using analytical and numerical methods.

• Received 7 July 1987

DOI:https://doi.org/10.1103/PhysRevD.36.3211