Strongly Coupled CFT in FRW Universe from AdS/CFT Correspondence

TL;DR

This paper develops a formalism using AdS/CFT correspondence to compute the effective action and two-point functions of strongly coupled CFTs in curved spacetimes like de Sitter and FRW universes, including vacuum state specification.

Contribution

It introduces a method to calculate the effective action and two-point functions of strongly coupled CFTs in curved spacetimes via AdS/CFT, including vacuum state determination.

Findings

Derived scalar two-point functions in de Sitter and FRW spacetimes.

Presented a method to specify the vacuum state in AdS/CFT.

Provided a simple derivation of counter terms using Hamilton-Jacobi equation.

Abstract

We develop a formalism to calculate the effective action of the strongly coupled conformal field theory (CFT) in curved spacetime. The effective action of the CFT is obtained from AdS/CFT correspondence. The anti de-Sitter (AdS) spacetime has various slicing which give various curved spacetime on its boundary. We show the de Sitter spacetime and the Friedmann-Robertson-Walker (FRW) universe can be embedded in the AdS spacetime and derive the scalar two-point function of the conformal fields in those spacetime. In curved spacetime, the two-point function depends on the vacuum state of the CFT. A method to specify the vacuum state in AdS/CFT calculations is shown. Because the classical action in AdS spacetime diverges near the boundary, we need the counter terms to regulate the result. The simple derivation of the counter terms using the Hamilton-Jacobi equation is also presented in the appendix.