Bottom-up holographic models for cosmology

TL;DR

This paper explores simplified holographic models for cosmology using boundary conformal field theories and branes, finding that certain generalizations are necessary for viable cosmological solutions.

Contribution

It introduces new generalizations of bottom-up holographic models for cosmology, including additional branes and Einstein-Hilbert terms, to achieve physically meaningful solutions.

Findings

Viable cosmological solutions require model generalizations.

Including an Einstein-Hilbert term enables solutions with physical relevance.

Models with additional interface branes are explored for cosmological applications.

Abstract

In this note, we investigate some simple generalizations of a bottom-up holographic approach to cosmology introduced in arXiv:1810.10601. Our models utilize the Karch/Randall/Takayanagi ansatz for the gravitational dual of a boundary conformal field theory, involving pure AdS gravity and an end-of-the-world brane. Following a suggestion made in arXiv:2102.05057, we consider models with an additional interface brane in the bulk. We find that solutions with a viable cosmological interpretation exist only if our model is further generalized, for example by including an Einstein-Hilbert term in the ETW brane action. The physical validity of such models is discussed from the perspective of the effective theory.