Double brane holographic model dual to 2d ICFTs

TL;DR

This paper introduces a double brane holographic model that better captures the range of interface properties in 2d ICFTs, allowing independent tuning of transmission and boundary entropy.

Contribution

The work proposes a double brane holographic setup that overcomes limitations of single-brane models by enabling independent control of transmission coefficient and boundary entropy.

Findings

Double brane model reproduces a wider range of transmission coefficients.

Merger of two single-brane interfaces creates new interface types.

Achieves the decoupled BCFT limit with zero transmission.

Abstract

A minimal single-brane holographic model can be used as a dual to 2d conformal interfaces (ICFTs) to calculate the transmission coefficient $\mathcal{T}$ of energy transported across the defect as well as boundary entropy $\log g$, the additional entanglement entropy for some sub-region that encloses the defect. Both $\mathcal{T}$ and $\log g$ are uniquely determined by the tension characterizing the brane. In contrast, in field theory defects typically the transmission coefficient can be dialed from 0 to 1 independently for each allowed value of $\log g$. To address this discrepancy, we look at a double brane (3-region bulk) holographic model. Merger of two single brane interfaces creates genuinely new interfaces which indeed allow a range of accessible transmission coefficients for a fixed value of $\log g$. In particular, the $\mathcal{T}=0$ limit of two completely decoupled BCFTs can be achieved.