A note on entanglement entropy and topological defects in symmetric orbifold CFTs

TL;DR

This paper calculates entanglement entropy in symmetric orbifold conformal field theories with topological defects, revealing how defects influence entropy and symmetry properties.

Contribution

It provides the first detailed computation of defect-induced entanglement entropy in symmetric orbifold CFTs, including both universal and non-universal defects.

Findings

Universal defects realize non-invertible symmetry $Rep(S_N)$

Sub-leading defect entropy/g-factor computed for boundary and interior defects

Insights into the role of topological defects in entanglement structure

Abstract

In this brief note we calculate the entanglement entropy in $M^{\otimes N}/S_N$ symmetric orbifold CFTs in the presence of topological defects, which were recently constructed in \cite{Gutperle:2024vyp,Knighton:2024noc}. We consider both universal defects which realize $Rep(S_N)$ non-invertible symmetry and non-universal defects. We calculate the sub-leading defect entropy/g-factor for defects at the boundary entangling surface as well as inside it.