The Radion Mode in Consistent Brane-World Reductions

TL;DR

This paper develops new consistent brane-world Kaluza-Klein reductions involving the radion mode, enabling matter supermultiplets coupled to supergravity from higher-dimensional pure gauged supergravity, and introduces broader classes of bosonic reductions with non-abelian gauge fields.

Contribution

It presents novel brane-world reductions that include the radion mode and demonstrates the existence of broader bosonic reductions with non-abelian gauge fields and Minkowski vacua.

Findings

Radion mode included in consistent reductions.

Matter supermultiplets coupled to supergravity achieved.

Non-abelian gauge fields with Minkowski solutions in lower dimensions.

Abstract

We construct consistent brane-world Kaluza-Klein reductions involving the radion mode that measures the separation of the domain-wall branes. In these new examples, we can obtain matter supermultiplets coupled to supergravity on the brane, starting from pure gauged supergravity in the higher dimension. This contrasts with previously-known examples of consistent brane-world reductions involving the radion, where either pure supergravity reduced to pure supergravity, or else supergravity plus matter reduced to supergravity plus matter. As well as considering supersymmetric reductions, we also show that there exist broader classes of consistent reductions of bosonic systems. These include examples where the lower-dimensional theory has non-abelian Yang-Mills fields and yet the scalar sector has a potential that admits Minkowski spacetime as a solution. Combined with a sphere reduction to obtain the starting point for the brane-world reduction, this provides a Kaluza-Klein mechanism for obtaining non-abelian gauge symmetries from the geometry of the reduction, whilst still permitting a Minkowski vacuum in the lower dimension.