Low-Energy Probes of a Warped Extra Dimension

TL;DR

This paper explores how a warped extra dimension model with a hidden U(1) gauge sector can be tested through fixed-target experiments by detecting mixing effects between KK modes and the standard model photon and Z boson.

Contribution

It introduces a novel setup with a second warped space containing a hidden U(1)_x gauge theory and analyzes its potential experimental signatures via gauge kinetic mixing.

Findings

Multiple KK modes can be probed in upcoming experiments.

Significant mixing with the standard model can occur for lightest and heavier KK modes.

The model provides a new method to investigate extra dimensions.

Abstract

We investigate a natural realization of a light Abelian hidden sector in an extended Randall-Sundrum (RS) model. In addition to the usual RS bulk we consider a second warped space containing a bulk U(1)_x gauge theory with a characteristic IR scale of order a GeV. This Abelian hidden sector can couple to the standard model via gauge kinetic mixing on a common UV brane. We show that if such a coupling induces significant mixing between the lightest U(1)_x gauge mode and the standard model photon and Z, it can also induce significant mixing with the heavier U(1)_x Kaluza-Klein (KK) modes. As a result it might be possible to probe several KK modes in upcoming fixed-target experiments and meson factories, thereby offering a new way to investigate the structure of an extra spacetime dimension.