Phase structure and monopoles in U(1) gauge theory

TL;DR

This paper explores the phase transitions in 4D U(1) lattice gauge theory with monopoles, revealing a shift from first to second order transitions as monopole effects are varied, linked to topological properties.

Contribution

It introduces a dynamical monopole coupling in the model and analyzes how this affects the phase transition order and topological characteristics.

Findings

Transition strength decreases with monopole coupling

Transition changes from first to second order

Phases are characterized by topological properties

Abstract

We investigate the phase structure of pure compact U(1) lattice gauge theory in 4 dimensions with the Wilson action supplemented by a monopole term. To overcome the suppression of transitions between the phases in the simulations we make the monopole coupling a dynamical variable. We determine the phase diagram and find that the strength of the first order transition decreases with increasing weight of the monopole term, the transition thus ultimately getting of second order. After outlining the appropriate topological characterization of networks of currents lines, we present an analysis of the occurring monopole currents which shows that the phases are related to topological properties.