Higgs production and decay processes via loop diagrams in various 6D Universal Extra Dimension models at LHC

We calculate loop-induced Higgs production and decay processes which are relevant for the LHC in various six-dimensional Universal Extra Dimension models. More concretely, we focus on the Higgs production through gluon fusion and the Higgs decay into two photons induced by loop diagrams. They are one-loop leading processes and the contribution of Kaluza-Klein particles is considered to be significant. These processes are divergent in six dimensions. Therefore, we employ a momentum cutoff, whose size is fixed from the validity of perturbative calculation through naive dimensional analysis. In these six-dimensional Universal Extra Dimension models, the Higgs production cross section through gluon fusion is highly enhanced and the Higgs decay width into two photons is suppressed. In particular in the case of the compactification on Projective Sphere, these effects are remarkable. The deviation of the h((0)) -> 2 gamma signal front the prediction of the Standard model is much greater than that in the case of the five-dimensional minimal UED model. We also consider threshold corrections in the two processes and these effect are noteworthy even when we take a higher cutoff and/or a heavy KK scale. Comparing our calculation to the recent LUC results which were published at the Lepton-Photon 2011 and at the December of 2011 is performed briefly.