Gauging C on the Lattice

TL;DR

This paper explores charge conjugation symmetry in lattice gauge theories, focusing on constructing an $O(2)$ gauge theory with non-invertible symmetries, and analyzes their implications for phase structure and operator behavior.

Contribution

It introduces a non-abelian Villain formulation for $O(2)$ gauge theory with gauged charge conjugation symmetry and studies the resulting higher-group and non-invertible symmetries.

Findings

Construction of gauge-invariant non-local operators including Wilson and 't Hooft lines

Preservation of higher-group and non-invertible symmetries in lattice discretization

Proposal of a phase diagram with emergent generalized symmetries

Abstract

We discuss general aspects of charge conjugation symmetry in Euclidean lattice field theories, including its dynamical gauging. Our main focus is $O(2) = U(1)\rtimes \mathbb{Z}_2 $ gauge theory, which we construct using a non-abelian generalization of the Villain formulation via gauging the charge conjugation symmetry of pure $U(1)$ gauge theory. We describe how to construct gauge-invariant non-local operators in a theory with gauged charge conjugation symmetry, and use it to define Wilson and 't Hooft lines as well as non-invertible symmetry operators. Our lattice discretization preserves the higher-group and non-invertible symmetries of $O(2)$ gauge theory, which we explore in detail. In particular, these symmetries give rise to selection rules for extended operators and their junctions, and constrain the properties of the worldvolume degrees of freedom on twist vortices (also known as Alice or Cheshire strings). We propose a phase diagram of the theory coupled to dynamical magnetic monopoles and twist vortices, where the various generalized symmetries are typically only emergent.