AdS and dS Braneworld Kaluza-Klein Reduction

TL;DR

This paper develops new consistent Kaluza-Klein reductions for braneworld scenarios, embedding four- and five-dimensional gauged supergravities into higher-dimensional theories, with applications to AdS and dS spaces and connections to string theory.

Contribution

It introduces novel consistent braneworld Kaluza-Klein reductions for gauged supergravities, including embeddings in type IIB and massive IIA supergravity, and explores analytic continuations to de Sitter spaces.

Findings

Derived 4D N=2 gauged supergravity on AdS_4 brane from 5D N=4 supergravity.

Obtained 5D N=2 gauged supergravity on AdS_5 brane from 6D N=4 supergravity.

Explored analytic continuations leading to de Sitter supergravity in 4D.

Abstract

We obtain new results for consistent braneworld Kaluza-Klein reductions, showing how we can derive four-dimensional N=2 gauged supergravity ``localised on the AdS_4 brane'' as an exact embedding in five-dimensional N=4 gauged supergravity. Similarly, we obtain five-dimensional N=2 gauged supergravity localised on an AdS_5 brane as a consistent Kaluza-Klein reduction from six-dimensional N=4 gauged supergravity. These embeddings can be lifted to type IIB and massive type IIA supergravity respectively. The new AdS braneworld Kaluza-Klein reductions are generalisations of earlier results on braneworld reductions to ungauged supergravities. The lower-dimensional cosmological constant in our AdS braneworld reductions is an adjustable parameter, and so it can be chosen to be small enough to be phenomenologically realistic, even if the higher-dimensional one is of Planck scale. We also discuss analytic continuations to give a de Sitter gauged supergravity in four dimensions as a braneworld Kaluza-Klein reduction. We find that there are two distinct routes that lead to the same four-dimensional theory. In one, we start from a five-dimensional de Sitter supergravity, which itself arises from a Kaluza-Klein reduction of type IIB^* supergravity on the hyperbolic 5-sphere. In the other, we start from AdS gauged supergravity in five dimensions, with an analytic continuation of the two 2-form potentials, and embed the four-dimensional de Sitter supergravity in that. The five-dimensional theory itself comes from an O(4,3)/O(3,2) reduction of Hull's type IIB_{7+3} supergravity in ten dimensions.