Heavy Higgs at Tevatron and LHC in Universal Extra Dimension Models

TL;DR

This paper explores how Universal Extra Dimension models predict a heavier Higgs boson that could explain certain excess events at the LHC, with potential observability at current collider energies.

Contribution

It demonstrates that weak scale UED models predict a heavy Higgs with enhanced production and decay signatures, providing a model-independent explanation for observed anomalies.

Findings

UED models predict a heavy Higgs around 250 GeV.

The model can account for the 2-sigma excess at ATLAS.

Significant resonance signals are observable at 10 fb^{-1} for 500 GeV Higgs.

Abstract

Universal Extra Dimension (UED) models tend to favor a distinctively heavier Higgs mass than in the Standard Model (SM) and its supersymmetric extensions when the Kaluza-Klein (KK) scale is not much higher than the electroweak one, which we call the weak scale UED, in order to cancel the KK top contributions to the T-parameter. Such a heavy Higgs, whose production through the gluon fusion process is enhanced by the KK top loops, is fairly model independent prediction of the weak scale UED models regardless of the brane-localized mass structure at the ultraviolet cutoff scale. We study its cleanest possible signature, the Higgs decay into a Z boson pair and subsequently into four electrons and/or muons, in which all the four-momenta of the final states can be measured and both the Z boson masses can be checked. We show that the weak scale UED model may account for the 2sigma excess of this event at ATLAS at the ZZ pair invariant mass around 250GeV, at which scale SM background is sufficiently small and the SM Higgs predicts too few events. We have also studied the Higgs mass 500GeV (and also 700GeV with \sqrt{s}=14TeV) and have found that we can observe significant resonance with the integrated luminosity 10fb^{-1} for six dimensional UED models.