Exploring causality in braneworld/cutoff holography via holographic scattering

TL;DR

This paper investigates causality and entropic properties in cutoff holography by proposing a new induced light cone framework, validating key theorems, and addressing apparent superluminal signaling artifacts.

Contribution

It introduces the concept of induced light cones for bulk scattering in cutoff holography and proves the connected wedge theorem and entropic inequalities within this framework.

Findings

Validated the connected wedge theorem for induced light cones.

Showed entropic inequalities hold in generalized holography.

Argued superluminal signaling is an artifact of state preparation.

Abstract

Holography with branes and/or cutoff surfaces presents a promising approach to studying quantum gravity beyond asymptotically anti-de Sitter spacetimes. However, this generalized holography is known to face several inconsistencies, including potential violations of causality and fundamental entropic inequalities. In this work, we address these challenges by investigating the bulk scattering process and its holographic realization. Specifically, we propose that the information on a brane/cutoff surface $Q$ propagates according to the induced light cones originating from a fictitious asymptotic boundary behind $Q$, rather than the conventional ones originating from a point on $Q$. Additionally, we establish the validity of the connected wedge theorem for generalized holography with induced light cones. We also demonstrate that entropic inequalities remain valid within the induced causal diamonds. While the induced light cone seemingly permits superluminal signaling, we argue that this causality violation can be an artifact of state preparation for radially propagating excitations, rather than local operator excitations on $Q$.