U(1) lattice gauge theory with a topological action

TL;DR

This paper explores the phase diagram of 4D compact U(1) lattice gauge theory using a topological action, revealing a weakly first order transition, a monopole-free phase, and computational benefits for free energy calculations.

Contribution

It introduces a topological action approach to U(1) lattice gauge theory, identifying new phase structures and computational advantages over traditional methods.

Findings

Identifies a weakly first order phase transition.

Discovers a phase with no magnetic monopoles.

Shows computational benefits for free energy calculations.

Abstract

We investigate the phase diagram of the compact $U(1)$ lattice gauge theory in four dimensions using a non-standard action which is invariant under continuous deformations of the plaquette angles. Just as for the Wilson action, we find a weakly first order transition, separating a confining phase where magnetic monopoles condense, and a Coulomb phase where monopoles are dilute. We also find a third phase where monopoles are completely absent. The topological action offers an algorithmic advantage for the computation of the free energy.