Boundary Modes in the Chamon Model

TL;DR

This paper investigates the boundary phenomena of the Chamon fracton model, revealing new boundary excitations, a continuum description akin to Chern-Simons theory, and conditions for stable gapless boundary phases.

Contribution

It introduces a diagrammatic framework for boundary excitations and demonstrates how continuum theories describe boundary gapped and gapless phases in the Chamon model.

Findings

Boundary excitations are characterized by a new diagrammatic approach.

Continuum theory describes boundary as scalar fields similar to Chern-Simons theory.

Stable gapless boundary phase exists under certain interaction conditions.

Abstract

We study the fracton phase described by the Chamon model in a manifold with a boundary. The new processes and excitations emerging at the boundary can be understood by means of a diagrammatic framework. From a continuum perspective, the boundary theory is described by a set of scalar fields in similarity with the standard $K$-matrix Chern-Simons theory. The continuum theory recovers the gapped boundaries of the lattice model once we include sufficiently strong interactions that break charge conservation. The analysis of the perturbative relevance of the leading interactions reveals a regime in which the Chamon model can have a stable gapless fractonic phase at its boundary.