  In our previous paper, we have investigated effects of a simple gauge-Higgs
unification model on the diphoton signal events from the Higgs boson production
at the Large Hadron Collider. We have found that in this model the effective
Higgs-to-diphoton coupling can be enhanced by 1-loop corrections with
Kaluza-Klein (KK) modes of bulk fields. This result can be an explanation for
the observed excess of the signal strength in the Higgs to diphoton decay
channel. In this paper, we investigate KK-mode effects on another Higgs boson
decay mode, H to Z gamma. One naturally expects that the KK modes also
contribute to the effective H-Z-gamma coupling and can cause some deviation for
the H to Z gamma decay mode from the Standard Model prediction. Revealing a
correlation between the KK-mode effects on the Higgs-to-diphoton and H-Z-gamma
couplings is an interesting topic in terms of a possibility to discriminate a
variety of models for physics beyond the Standard Model. We show a very
striking result for the gauge-Higgs unification model, namely, the absence of
KK-mode contributions to the H-Z-gamma coupling at the 1-loop level. This is a
very specific and general prediction of the gauge-Higgs unification scenario.
