Phenomenology of a Stabilized Modulus

TL;DR

This paper investigates the properties and potential experimental signatures of a stabilized modulus (radion) in the Randall-Sundrum model, highlighting its lightness and couplings to Standard Model fields.

Contribution

It demonstrates that the radion can be lighter than Kaluza-Klein modes and its couplings are uniquely determined by a single parameter related to the TeV scale.

Findings

Radion is likely the lightest Kaluza-Klein excitation.

Couplings to Standard Model are fixed by four-dimensional covariance.

Radion could be the first detectable signature of the model.

Abstract

We explore the phenomenology of a stabilized modulus field in the Randall-Sundrum scenario. It is found that if the large separation between branes arises from a small bulk scalar mass then the modulus (i.e. radion) is likely to be lighter than the lowest Kaluza-Klein excitations of bulk fields, and consequently may be the first direct signature of the model. Four-dimensional general covariance completely determines the couplings of the modulus to Standard Model fields. The strength of these couplings is determined by a single parameter which is set by the TeV rather than the Planck scale.