A novel braneworld model with a bulk scalar field

TL;DR

This paper introduces a new braneworld model with a bulk scalar field inspired by tachyon vacuum physics, resulting in non-singular warped geometries that address the hierarchy problem and localize gravity and fermions.

Contribution

It proposes a novel Einstein-scalar system with a specific potential, yielding unique warped solutions that differ quantitatively from Randall--Sundrum models.

Findings

Non-singular warped geometries with decaying warp factor

Solution to the hierarchy problem via this warping

Localization of graviton zero mode and massless fermions on the brane

Abstract

We consider a new braneworld model with a bulk scalar field coupled to gravity. The bulk scalar action is inspired by the proposed low energy effective action around the tachyon vacuum. A class of warped geometries representing solutions of this Einstein-scalar system for a specific scalar potential is found. The geometry is non singular with a decaying warp factor and a negative Ricci curvature. The solution of the hierarchy problem is obtained using this type of warping. Though qualitatively similar to the usual Randall--Sundrum I model there are interesting quantitative differences. Additionally, in the RS-II set up the graviton zero mode as well as spin half massless fermions are found to be localised on the brane.