Non-minimal universal extra dimensions

TL;DR

This paper explores how boundary localized terms in non-minimal universal extra dimensions models alter the Kaluza-Klein spectrum and couplings, impacting experimental constraints and the identity of the lightest KK particle.

Contribution

It provides a detailed analysis of the effects of boundary localized terms on the KK spectrum and couplings, highlighting their significant impact on model phenomenology.

Findings

Boundary localized terms modify the KK mass spectrum and profiles.

Constraints on boundary localized terms are weak from current experiments.

Non-zero boundary localized terms can change the identity of the lightest KK particle.

Abstract

In this paper we investigate the phenomenological implications of boundary localized terms (BLTs) in the model of Universal Extra Dimensions (UED). In particular, we study the electroweak Kaluza-Klein mass spectrum resulting from BLTs and their effect on electroweak symmetry breaking via the five dimensional Higgs mechanism. We find that the addition of BLTs to massive five dimensional fields induces a non-trivial extra dimensional profile for the zero and non-zero Kaluza-Klein (KK) modes. Hence BLTs generically lead to a modification of Standard Model parameters and are therefore experimentally constrained, even at tree level. We study Standard Model constraints on three representative non-minimal UED models in detail and find that the constraints on BLTs are weak. On the contrary, non-zero BLTs have a major impact on the spectrum and couplings of non-zero KK modes. For example, there are regions of parameter space where the Lightest Kaluza-Klein particle (LKP) is either the Kaluza-Klein Higgs boson or the first KK mode of the W^3.