Hybrid brane worlds in the Salam-Sezgin model

TL;DR

This paper constructs a novel 6D brane world model based on Salam-Sezgin supergravity, demonstrating localized gravity, potential hierarchy problem solutions, and black hole embeddings within a hybrid Kaluza-Klein/Randall-Sundrum framework.

Contribution

It introduces a unique hybrid brane world construction in six dimensions that differs from existing models and includes exact solutions like gravitational waves and black holes.

Findings

Localized Newtonian gravity with Yukawa corrections

Parameter ranges potentially solve the hierarchy problem

Exact nonlinear gravitational wave solutions

Abstract

We construct a 6-dimensional warped brane world compactification of the Salam-Sezgin supergravity model by generalizing an earlier hybrid Kaluza-Klein / Randall-Sundrum construction [hep-th/0109099]. In this construction the observed universe is interpreted as a 4-brane in six dimensions, with a Kaluza-Klein spatial direction in addition to the usual three noncompact spatial dimensions. This construction is distinct from other brane world constructions in six dimensions, which introduce the universe as a 3-brane corresponding to a topological defect in six dimensions, or which require a particular configuration of matter fields on the brane. We demonstrate that the model reproduces localized gravity on the brane in the expected form of a Newtonian potential with Yukawa-type corrections. We show that allowed parameter ranges include values which potentially solve the hierarchy problem. An exact nonlinear gravitational wave solution on the background is exhibited. The class of solutions given applies to Ricci-flat geometries in four dimensions, and consequently includes brane world realizations of the Schwarzschild and Kerr black holes as particular examples. Arguments are given which suggest that the hybrid compactification of the Salam-Sezgin model can be extended to reductions to arbitrary Einstein space geometries in four dimensions.