Inflation in AdS/CFT

TL;DR

This paper explores how the AdS/CFT correspondence can be used to understand inflation, showing that inflating regions are represented as mixed states in the boundary CFT and that no scattering process can generate inflationary regions.

Contribution

It introduces a novel framework connecting inflationary bubbles in the bulk with mixed states in the boundary CFT within the AdS/CFT correspondence.

Findings

Inflating bubbles correspond to mixed states in the boundary CFT.

Analytic continuation links AdS/CFT to dS/CFT correlators.

Pure states cannot evolve into mixed states via unitary processes.

Abstract

We study the AdS/CFT correspondence as a probe of inflation. We assume the existence of a string landscape containing at least one stable AdS vacuum and a (nearby) metastable de Sitter state. Standard arguments imply that the bulk physics in the vicinity of the AdS minimum is described by a boundary CFT. We argue that large enough bubbles of the dS phase, including those able to inflate, are described by mixed states in the CFT. Inflating degrees of freedom are traced over and do not appear explicitly in the boundary description. They nevertheless leave a distinct imprint on the mixed state. In the supergravity approximation, analytic continuation connects AdS/CFT correlators to dS/CFT correlators. This provides a framework for extracting further information as well. Our work also shows that no scattering process can create an inflating region, even by quantum tunneling, since a pure state can never evolve into a mixed state under unitary evolution.