Particle Physics Probes Of Extra Spacetime Dimensions

TL;DR

The paper addresses whether spacetime may possess extra dimensions and how such dimensions could be probed at TeV scales. It analyzes two main frameworks—ADD large extra dimensions with gravity in the bulk and Standard Model fields on a brane, and warped (Randall–Sundrum) scenarios—deriving KK graviton spectra, radion phenomenology, and collider/gravitation signatures. It identifies two primary collider observables: real emission of KK gravitons resulting in missing energy and virtual KK graviton exchange modifying Standard Model cross sections, while also discussing short-range gravity tests and astrophysical/cosmological constraints. The findings show current data constrain the fundamental scale $M_D$ and the number of extra dimensions $\delta$ to a TeV or multi-TeV range depending on the model, with future experiments (e.g., the LHC) capable of fully exploring the viable parameter space and potentially revealing the geometry and dynamics of extra dimensions.

Abstract

The possibility that spacetime is extended beyond the familiar 3+1-dimensions has intrigued physicists for a century. Indeed, the consequences of a dimensionally richer spacetime would be profound. Recently, new theories with higher dimensional spacetimes have been developed to resolve the hierarchy problem in particle physics. These scenarios make distinct predictions which allow for experiment to probe the existence of extra dimensions in new ways. We review the conceptual framework of these scenarios, their implications in collider and short-range gravity experiments, their astrophysical and cosmological effects, as well as the constraints placed on these models from present data.