Search for Higgs bosons of the Universal Extra Dimensions at the Large Hadron Collider

TL;DR

This paper investigates the phenomenology of Higgs bosons in Universal Extra Dimensions at the LHC, focusing on their production, decay, and detection challenges due to mass degeneracies in the minimal UED model.

Contribution

It provides a detailed analysis of KK-Higgs states, their decay modes, production mechanisms, and discusses the experimental difficulties in observing them at the LHC.

Findings

KK-Higgs bosons have specific decay branching fractions.

Associated production with third-generation KK-quarks is significant.

Mass degeneracies cause detection challenges at the LHC.

Abstract

The Higgs sector of the Universal Extra Dimensions (UED) has a rather involved setup. With one extra space dimension, the main ingredients to the construct are the higher Kaluza-Klein (KK) excitations of the Standard Model Higgs boson and the fifth components of the gauge fields which on compactification appear as scalar degrees of freedom and can mix with the former thus leading to physical KK-Higgs states of the scenario. In this work, we explore in detail the phenomenology of such a Higgs sector of the UED with the Large Hadron Collider (LHC) in focus. We work out relevant decay branching fractions involving the KK-Higgs excitations. Possible production modes of the KK-Higgs bosons are then discussed with an emphasis on their associated production with the third generation KK-quarks and that under the cascade decays of strongly interacting UED excitations which turn out to be the only phenomenologically significant modes. It is pointed out that the collider searches of such Higgs bosons face generic hardship due to soft end-products which result from severe degeneracies in the masses of the involved excitations in the minimal version of the UED (MUED). Generic implications of either observing some or all of the KK-Higgs bosons at the LHC are discussed.