A Large Mass Hierarchy from a Small Extra Dimension

TL;DR

The paper introduces a higher-dimensional solution to the hierarchy problem using a single extra dimension with a warped AdS5 metric between two 3-branes. The warp factor e^{-k r_c π} links fundamental high-energy parameters to TeV-scale physics on the visible brane, generating the weak scale without large extra dimensions. It predicts TeV-scale Kaluza-Klein gravitons with weak-scale couplings and no light KK modes, yielding distinctive collider signatures and requiring new phenomenological analyses beyond the Standard Model. Open issues include stabilizing the extra dimension and addressing potential flavour constraints, but the framework offers testable predictions at the LHC via spin-2 resonances and related TeV-scale phenomena.

Abstract

We propose a new higher-dimensional mechanism for solving the Hierarchy Problem. The Weak scale is generated from a large scale of order the Planck scale through an exponential hierarchy. However, this exponential arises not from gauge interactions but from the background metric (which is a slice of AdS_5 spacetime). This mechanism relies on the existence of only a single additional dimension. We demonstrate a simple explicit example of this mechanism with two three-branes, one of which contains the Standard Model fields. The experimental consequences of this scenario are new and dramatic. There are fundamental spin-2 excitations with mass of weak scale order, which are coupled with weak scale as opposed to gravitational strength to the standard model particles. The phenomenology of these models is quite distinct from that of large extra dimension scenarios; none of the current constraints on theories with very large extra dimensions apply.