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Radiative corrections to the Higgs boson couplings in the triplet model

We calculate a full set of one-loop corrections to the Higgs boson coupling constants as well as the electroweak parameters. We compute the decay rate of the standard model (SM)-like Higgs boson ($h$) into diphoton. Renormalized Higgs couplings with the weak gauge bosons $hVV$ ($V=W$ and $Z$) and the trilinear coupling $hhh$ are also calculated at the one-loop level in the on-shell scheme. Magnitudes of the deviations in these quantities are evaluated in the parameter regions where the unitarity and vacuum stability bounds are satisfied and the predicted W boson mass at the one-loop level is consistent with the data. We find that there are strong correlations among deviations in the Higgs boson couplings $hγγ$, $hVV$ and $hhh$. For example, if the event number of the $pp\to h\toγγ$ channel deviates by +30% (-40%) from the SM prediction, deviations in the one-loop corrected $hVV$ and $hhh$ vertices are predicted about -0.1% (-2%) and -10% $(+150%)$, respectively. The model can be discriminated from the other models by measuring these coupling constants accurately at future collider experiments.