Kenji Nishiwaki, Kin-ya Oda, Naoya Okuda, Ryoutaro Watanabe
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.
View original:
http://arxiv.org/abs/1108.1765
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