Double holography in string theory

TL;DR

This paper develops a detailed string theory framework for double holography involving Type IIB setups, providing microscopic realizations and analyzing causal structures in dual descriptions of boundary conformal field theories.

Contribution

It introduces a string theory-based realization of double holography for BCFTs, clarifies the intermediate holographic description, and refines the understanding of causal structures in these models.

Findings

Confirmed qualitative features of causal structures in BCFT duals.

Provided microscopic brane constructions for intermediate holographic descriptions.

Suggested refinements to the interpretation of causal features in bottom-up models.

Abstract

We develop the notion of double holography in Type IIB string theory realizations of braneworld models. The Type IIB setups are based on the holographic duals of 4d BCFTs comprising 4d $\mathcal N=4$ SYM on a half space coupled to 3d $\mathcal N=4$ SCFTs on the boundary. Based on the concrete BCFTs and their brane construction, we provide microscopic realizations of the intermediate holographic description, obtained by dualizing only the 3d degrees of freedom. Triggered by recent observations in bottom-up models, we discuss the causal structures in the full BCFT duals and intermediate descriptions. This confirms qualitative features found in the bottom-up models but suggests a refinement of their interpretation.