Localization of gravity on a de Sitter thick braneworld without scalar fields

TL;DR

This paper introduces a simple thick braneworld model with a de Sitter metric that localizes 4D gravity without scalar fields, featuring a mass gap in the graviton spectrum and smooth curvature along the extra dimension.

Contribution

It presents a novel scalar-field-free thick brane model with a de Sitter brane, demonstrating localized gravity, a mass gap in KK modes, and no naked singularities.

Findings

4D gravity is localized on the brane

The graviton spectrum has a mass gap

The model avoids naked singularities

Abstract

In this work we present a simple thick braneworld model that is generated by an intriguing interplay between a 5D cosmological constant with a de Sitter metric induced in the 3-brane without the inclusion of scalar fields. We show that 4D gravity is localized on this brane, provide analytic expressions for the massive Kaluza-Klein (KK) fluctuation modes and also show that the spectrum of metric excitations displays a mass gap. We finally present the corrections to Newton's law due to these massive modes. This model has no naked singularities along the fifth dimension despite the existence of a mass gap in the graviton spectrum as it happens in thick branes with 4D Poincare symmetry, providing a simple model with very good features: the curvature is completely smooth along the fifth dimension, it localizes 4D gravity and the spectrum of gravity fluctuations presents a mass gap, a fact that rules out the existence of phenomenologically dangerous ultralight KK excitations in the model. We finally present our solution as a limit of scalar thick branes.