A universe in a global monopole

TL;DR

This paper explores brane physics within a universe featuring a global monopole and negative cosmological constant, demonstrating how four-dimensional gravity and matter can emerge from higher-dimensional models with a specific spectrum of modes.

Contribution

It introduces a model where a global monopole in extra dimensions induces four-dimensional gravity and matter fields, addressing the hierarchy problem through parameter choices.

Findings

Graviton zero mode divergence is managed via a physical cut-off.

Kaluza-Klein modes produce a discrete spectrum compatible with 4D gravity.

Extra dimensional matter fields generate 4D matter with a similar spectrum.

Abstract

We investigate brane physics in a universe with an extra dimensional global monopole and negative bulk cosmological constant. The graviton zero mode is naturally divergent; we thus invoke a physical cut-off to induce four dimensional gravity on a brane at the monopole core. Independently, the massive Kaluza-Klein modes have naturally compactified extra dimensions, inducing a discrete spectrum. This spectrum remains consistent with four dimensional gravity on the brane, even for small mass gap. Extra dimensional matter fields also induce four dimensional matter fields on the brane, with the same Kaluza-Klein spectrum of excited states. We choose parameters to solve the hierarchy problem; that is, to induce the observed hierarchy between particle and Planck scales in the effective four dimensional universe.