Connecting boundary entropy and effective central charge at holographic interfaces

TL;DR

This paper explores how boundary entropy and effective central charge relate in holographic interface CFTs, revealing their connection through holographic duals and implications for entanglement entropy.

Contribution

It demonstrates that the effective central charge modification can be derived as a limit of boundary entropy in holographic interface CFTs.

Findings

Effective central charge is a limit of boundary entropy in holographic models.

Finite boundary contributions are necessary for strong subadditivity.

The study links boundary entropy with effective central charge in holographic duals.

Abstract

The entanglement entropy of intervals in $1+1$ interface CFTs is modified in two ways compared to a CFT without interface: there is a finite boundary entropy contribution, and, for an interval with an endpoint at the interface, the coefficient of the logarithmically divergent contribution -- which is usually proportional to the central charge of the CFT -- is modified to an effective central charge. We show that the latter modification can be understood as a limit of the former using holographic duals of interface CFTs. Furthermore, we show that a finite contribution also appears in intervals that do not cross the interface and it is needed to ensure strong subbaditivity of the entanglement entropy.