Dark Matter in Minimal Universal Extra Dimensions with a Stable Vacuum and the "Right" Higgs

Understand

The recent discovery of a Higgs boson with mass of about 125 GeV, along with its striking similarity to the prediction from the Standard Model, informs and constrains many models of new physics.

• The Higgs mass exhausts one out of three input parameters of the minimal, five-dimensional version of universal extra dimension models, the other two parameters being the Kaluza-Klein (KK) scale and the cut-off scale of the theory.
• The presence of KK fermions with large coupling to the Higgs implies a short-lived electro-weak vacuum, unless the cut-off scale is at most a few times higher than the KK mass scale, providing an additional tight constraint to the theory parameter space.
• Here, we focus on the lightest KK particle as a dark matter candidate, and investigate the regions of parameter space where such particle has a thermal relic density in accord with the cosmological dark matter density.