Effects of SM Kaluza-Klein excitations on electroweak observables

TL;DR

This paper investigates how Kaluza-Klein excitations from an extra dimension influence electroweak measurements, providing bounds on the size of the extra dimension using precision data.

Contribution

It introduces a comprehensive analysis of Kaluza-Klein effects on electroweak observables and derives model-independent constraints on the extra dimension scale.

Findings

Bounds on 1/R range from 1 to 3 TeV.

Model-independent limit of 2.5 TeV on the extra dimension.

Electroweak observables are sensitive to Kaluza-Klein excitations.

Abstract

The presence of an extra dimension of size R \approx TeV^{-1} introduces a tower of Kaluza-Klein gauge boson excitations that affects the standard model (SM) relations between electroweak observables. The mixing of the W and Z bosons with their excitations changes their masses and couplings to fermions. This effect depends on the Higgs field, which may live in the bulk of the extra dimension, on its boundary, or may be a combination of both types of fields. We use high-precision electroweak data to constrain 1/R. We find limits from 1 to 3 TeV from different observables, with a model independent bound of 2.5 TeV.