Weak mixing angle and Higgs mass in Gauge-Higgs unification models with brane kinetic terms

Abstract

We show that the idea of Gauge-Higgs unification(GHU) can be rescued from the constraint of weak mixing angle by introducing localized brane kinetic terms in higher dimensional GHU models with bulk and simple gauge groups. We find that those terms lead to a ratio between Higgs and W boson masses, which is a little bit deviated from the one derived in the standard model. From numerical analysis, we find that the current lower bound on the Higgs mass tends to prefer to exceptional groups E _{6, 7, 8} rather than other groups like SU(3l), SO(2n+1), G ₂, and F ₄ in 6-dimensional (D) GHU models irrespective of the compactification scales. For the compactification scale below 1 TeV, the Higgs masses in 6D GHU models with SU(3l), SO(2n + 1), G ₂, and F ₄ groups are predicted to be less than the current lower bound unless a model parameter responsible for re-scaling SU(2) gauge coupling is taken to be unnaturally large enough. To see how the situation is changed in more higher dimensional GHU model, we take 7D S ³ / ${\mathbb{Z}_2}$ and 8D T ⁴ /Z ₂ models. It turns out from our numerical analysis that these higher dimensional GHU models with gauge groups except for E ₆ can lead to the Higgs boson whose masses are predicted to be above the current lower bound only for the compatification scale above 1 TeV without taking unnaturally large value of the model parameter, whereas the Higgs masses in the GHU models with E ₆ are compatible with the current lower bound even for the compatification scale below 1 TeV.