Radiative corrections to the Higgs couplings in the triplet model

The feature of extended Higgs models can appear in the pattern of deviations from the Standard Model (SM) predictions in coupling constants of the SM-like Higgs boson ($h$). We can thus discriminate extended Higgs models by precisely measuring the pattern of deviations in the coupling constants of $h$, even when extra bosons are not found directly. In order to compare the theoretical predictions to the future precision data at the ILC, we must evaluate the theoretical predictions with radiative corrections in various extended Higgs models. In this talk, we give our comprehensive study for radiative corrections to various Higgs boson couplings of $h$ in the minimal Higgs triplet model (HTM). First, we define renormalization conditions in the model, and we calculate the Higgs coupling; $g\gamma\gamma, hWW, hZZ$ and $hhh$ at the one loop level. We then evaluate deviations in coupling constants of the SM-like Higgs boson from the predictions in the SM. We find that one-loop contributions to these couplings are substantial as compared to their expected measurement accuracies at the ILC. Therefore the HTM has a possibility to be distinguished from the other models by comparing the pattern of deviations in the Higgs boson couplings.Comment: 6 pages, 2 eps figures, Proceedings of LC13: Exploring QCD from the infrared regime to heavy flavour scales at B-factories, the LHC and a Linear Collider, 16-20 September, 2013, ECT*, Villa Tambosi, Vallazzano(TN), Italy. arXiv admin note: text overlap with arXiv:1305.010

Approximate Alignment in Two Higgs Doublet Model with Extra Yukawa Couplings

With discovery of the 125 GeV boson $h^0$, the existence of a second doublet is very plausible. We show that the "alignment" phenomenon, that $h^0$ is found to resemble closely the Standard Model Higgs boson, may correspond to Higgs quartic couplings $\eta_i$ that are ${\cal O}(1)$ in strength. If the exotic bosons of the second doublet possess extra top Yukawa couplings, which are the least constrained by data, such a two Higgs doublet model could drive electroweak baryogenesis, as well as further "protect" the apparent alignment. The exotic Higgs bosons can be sub-TeV in mass while remaining well hidden so far, with broad parameter space for search at the Large Hadron Collider.Comment: Final version corresponding to acceptance by Euro. Phys. Let

Radiative corrections to the Yukawa coupling constants in two Higgs doublet models

We calculate one-loop corrected Yukawa coupling constants $hf\bar{f}$ for the standard model like Higgs boson $h$ in two Higgs doublet models. We focus on the models with the softly-broken $Z_2$ symmetry, which is imposed to avoid the flavor changing neutral current. Under the $Z_2$ symmetry, there are four types of Yukawa interactions. We find that one-loop contributions from extra Higgs bosons modify the $hf\bar{f}$ couplings to be maximally about $5\%$ under the constraint from perturbative unitarity and vacuum stability. Our results show that the pattern of tree-level deviations by the mixing effect in each type of Yukawa couplings from the SM predictions does not change even including radiative corrections. Moreover, when the gauge couplings $hVV$ ($V=W,Z$) are found to be slightly (with a percent level) differ from the SM predictions, the $hf\bar{f}$ couplings also deviate but more largely. Therefore, in such a case, not only can we determine the type of Yukawa couplings but also we can obtain information on the extra Higgs bosons by comparing the predictions with precisely measured $hf\bar{f}$ and $hVV$ couplings at future electron-positron colliders.Comment: Version accepted in Physics Letters