The second Kaluza-Klein mode of CP-odd neutral Higgs boson in the minimal universal extra dimension model

Loop-induced decays of a neutral standard model (SM) Higgs boson into a pair of gluons or photons are very suppressed if the Higgs boson is heavy (≳500GeV). In the minimal universal extra dimension model, these radiative decays can be significant for the second Kaluza-Klein (KK) mode of the CP-odd Higgs boson, χ(2). We find that the CP-even KK Higgs boson has vanishing decay rate of h(2)→gg at one-loop level: the h(2) production at the LHC is very suppressed. On the contrary, the process gg→χ(2)→γγ in an optimal scenario can be observed with manageable SM backgrounds at the LHC.