Lattice Abelian-Higgs model with noncompact gauge fields

We consider a noncompact lattice formulation of the three-dimensional electrodynamics with N-component complex scalar fields, i.e., the lattice Abelian-Higgs model with noncompact gauge fields. For any N >= 2, the phase diagram shows three phases differing for the behavior of the scalar-field and gauge-field correlations: The Coulomb phase (short-ranged scalar and long-ranged gauge correlations), the Higgs phase (condensed scalar-field and gapped gauge correlations), and the molecular phase (condensed scalar-field and long-ranged gauge correlations). They are separated by three transition lines meeting at a multicritical point. Their nature depends on the phases they separate, and on the number N of components of the scalar field. In particular, the Coulomb-to-molecular transition line (where gauge correlations are irrelevant) is associated with the Landau-Ginzburg-Wilson Phi(4) theory sharing the same SU(N) global symmetry but without explicit gauge fields. On the other hand, the Coulomb-to-Higgs transition line (where gauge correlations are relevant) turns out to be described by the continuum Abelian-Higgs field theory with explicit gauge fields. Our numerical study is based on finite-size scaling analyses of Monte Carlo simulations with C* boundary conditions (appropriate for lattice systems with noncompact gauge variables, unlike periodic boundary conditions), for several values of N, i.e., N = 2, 4, 10, 15, and 25. The numerical results agree with the renormalization-group predictions of the continuum field theories. In particular, the Coulomb-to-Higgs transitions are continuous for N >= 10, in agreement with the predictions of the Abelian-Higgs field theory.

Automated summary

The study investigates a noncompact lattice formulation of three-dimensional electrodynamics with N-component complex scalar fields, showing a phase diagram with three distinct phases: Coulomb phase, Higgs phase, and molecular phase separated by transition lines meeting at a multicritical point. The transitions are described by various continuum field theories with explicit or implicit gauge fields, and the numerical results are consistent with renormalization-group predictions for consecutive Coulomb-to-Higgs transitions.