Dynamical Electroweak Symmetry Breaking in $SO(5) \times U(1)$ Gauge-Higgs Unification in the Randall-Sundrum Warped Space

Abstract

In the gauge-Higgs unification scenario the Higgs field is unified with gauge fields in higher dimensional gauge theory. The 4D Higgs field $H(x)$ corresponds to 4D fluctuations of the Aharonov-Bohm phase (Wilson line phase) $\theta_H$ in the extra-dimension. An $SO(5)\times U(1)$ gauge-Higgs unification model in the Randall-Sundrum warped spacetime with top and bottom quarks is presented. Gauge couplings of the top quark multiplet induce electroweak symmetry breaking by the Hosotani mechanism. The effective potential $V_\eff (\theta_H)$ is found to be minimized at $\theta_H = \onehalf \pi$ and the Higgs mass is predicted around 50 GeV. The $ZZH$ and $WWH$ couplings vanish at $\theta_H = \onehalf \pi$ so that the LEP2 bound for the Higgs mass is evaded. The result is summarized in the effective interactions for $\hat \theta_H(x) = \theta_H + H(x)/f_H$.