Degenerate Higgs bosons decays toγγandZγin the type II seesaw model

Abstract

Using the most recent results of CMS and ATLAS, we study the Higgs decays to γγ and Zγ in the scenario where the two CP even Higgs predicted by the type II seesaw model (HTM) are close to mass degenerate with a mass near 125 GeV. We analyse the effects of the Higgs potential parameters constrained by the full set of perturbative unitarity, boundedness from below (BFB) as well as from precision electroweak measurements on these decay modes. Our analysis demonstrates that the observed excess in the diphoton Higgs decay channel can be interpreted in our scenario within a delineated region controlled by λ 1 and λ 4 coupling. We also find a deviation in the Higgs decay to Zγ with respect to the Standard Model prediction and the largest enhancement is found for a ratio R Zγ of the order 1.6. Furthermore we show that consistency with current ATLAS data on the diphoton decay channel favours a light doubly charged Higgs with mass in the range 92 − 180 GeV. Finally, we find that the γγ and Zγ Higgs decay modes are generally correlated and the magnitude of correlation is sensitive to the sign of the λ 1 parameter.

Neutrinos and collider physics

“…A future lepton collider such as the ILC will offer an almost background-free environment for the doubly charged scalar detection, if kinematically allowed, through the single production process e e e ℓ Δ → + − ± ± ∓∓ [274] or pair-production process e e Δ Δ → + − ++ −− [275]. We note here that a relatively light charged scalar will affect the loop-induced decays of the SM Higgs boson h γγ → [260,[276][277][278][279][280][281] and h Zγ → [278][279][280][281][282]. In fact, for a given enhancement in these decay rates over the SM prediction, one can set an upper limit on the charged scalar mass in the minimal type-II seesaw model using vacuum stability and perturbative arguments [279].…”

Neutrinos and Collider Physics

“…A future lepton collider such as the ILC will offer an almost background-free environment for the doubly charged scalar detection, if kinematically allowed, through the single production process e e e ℓ Δ → + − ± ± ∓∓ [274] or pair-production process e e Δ Δ → + − ++ −− [275]. We note here that a relatively light charged scalar will affect the loop-induced decays of the SM Higgs boson h γγ → [260,[276][277][278][279][280][281] and h Zγ → [278][279][280][281][282]. In fact, for a given enhancement in these decay rates over the SM prediction, one can set an upper limit on the charged scalar mass in the minimal type-II seesaw model using vacuum stability and perturbative arguments [279].…”

Future prospects of mass-degenerate Higgs bosons in the CP -conserving two-Higgs-doublet model

“…where the current LHC measurements of signal strengths and errors of (µ PD exp , σ PD exp ) are summarized in Tables I and II for the run-I and run-II data, respectively. This scenario was previously explored in Refs. [3][4][5][6][7], where the total signal rates for 125 GeV Higgs boson were estimated by simple summation of σ × Br from the individual contribution of h and H as…”