Collider signatures of the SO(5) x U(1) gauge-Higgs unification

Abstract

Collider signatures of the $SO(5) \times U(1)$ gauge-Higgs unification model in the Randall-Sundrum warped space are explored. Gauge couplings of quarks and leptons receive small corrections from the fifth dimension whose effects are tested by the precision data. It is found that the forward-backward asymmetries in $e^+e^-$ collisions on the $Z$ pole are well explained in a wide range of the warp factor $z_L$, but the model is consistent with the branching fractions of $Z$ decay only for large $z_L \simg 10^{15}$. Kaluza-Klein (KK) spectra of gauge bosons, quarks, and leptons as well as gauge and Higgs couplings of low-lying KK excited states are determined. Right-handed quarks and leptons have larger couplings to the KK gauge bosons than left-handed ones. Production rates of Higgs bosons and KK states at Tevatron, LHC and ILC are evaluated. The first KK $Z$ has a mass 1130 GeV with a width 422 GeV for $z_L = 10^{15}$. The current limit on the $Z'$ production at Tevatron and LHC indicates $z_L >10^{15}$. A large effect of parity violation appears in the difference between the rapidity distributions of $e^+$ and $e^-$ in the decay of the first KK $Z$. The first KK gauge bosons decay into light and heavy quarks evenly.