$W$ and $Z$ boson pair production at electron-positron colliders in gauge-Higgs unification

We examine $W$ and $Z$ boson pair production processes at electron-positron collider experiments in the $SU(3{)}_C\times SO(5{)}_W\times U(1{)}_X$ gauge-Higgs unification (GHU) model. We find that the deviation of the total cross section for the $e^{-}{e}^{+}\to W^{-}{W}^{+}$ process from the Standard Model (SM) in the GHU model with parameter sets, which are consistent with the current experiments, is about 0.5% to 1.5% and 0.6% to 2.2% for $\sqrt{s}=250\mathrm{GeV}$ and 500 GeV, respectively, depending on the initial electron and positron polarization. We find that for the $e^{-}{e}^{+}\to ZZ$ process the deviation from the SM in the GHU model is at most 1%. We find that unitarity bound for the $e^{-}{e}^{+}\to W^{-}{W}^{+}$ process is satisfied in the GHU model as in the SM, as a consequence of the relationship among coupling constants.