h \gamma \gamma Coupling in Higgs Triplet Model

We investigate Higgs boson decay into two photons in the type-II seesaw model. The rate of $h\to \gamma\gamma$ gets suppressed/enhanced in this model compared to the Standard Model (SM) due to the presence of the singly and doubly charged Higgs $H^\pm$ and $H^{\pm\pm}$.Comment: Latex, 7 pages, 2 Figures. The 2011 International Workshop on Future Linear Colliders (LCWS11), Granada, Spai

The Higgs Potential in the Type II Seesaw Model

We perform in the type II seesaw setting, a detailed study of the dynamical features of the corresponding general renormalizable doublet/triplet Higgs potential that depends on five dimensionless couplings and two mass parameters after spontaneous symmetry breaking, and highlight the implications for the Higgs phenomenology. In particular, we determine i) the complete set of tree-level unitarity constraints on the couplings of the potential and ii) the exact tree-level {\sl all directions} boundedness from below constraints on these couplings. When combined, these constraints delineate precisely the theoretically allowed parameter space domain within our perturbative approximation. Among the seven physical Higgs states of this model, the mass of the lighter (heavier) CP-even state h0 (H0) will always satisfy a theoretical upper (lower) bound that is reached for a critical value mu_c of mu (the mass parameter controlling triple couplings among the doublet/triplet Higgses). Saturating the unitarity bounds we find m_h0 < {\cal O}(0.7 - 1 TeV), while the upper bound for the remaining Higgses lies in the several tens of TeV. However, the actual masses can be much lighter. We identify two regimes corresponding to mu > mu_c and mu < mu_c. In the first regime the Higgs sector is typically very heavy and only h0 that becomes SM-like could be accessible to the LHC. In contrast, in the second regime, somewhat overlooked in the literature, most of the Higgs sector is light. In particular the heaviest state H0 becomes SM-like, the lighter states being the CP-odd Higgs, the (doubly) charged Higgses and a decoupled h0, possibly leading to a distinctive phenomenology at the colliders.Comment: 55 pages, 9 figures, no major changes, references added, a comment added to sec 3.1, typos correcte

Higgs boson decay into 2 photons in the type~II Seesaw Model

We study the two photon decay channel of the Standard Model-like component of the CP-even Higgs bosons present in the type II Seesaw Model. The corresponding cross-section is found to be significantly enhanced in parts of the parameter space, due to the (doubly-)charged Higgs bosons' $(H^{\pm \pm})H^\pm$ virtual contributions, while all the other Higgs decay channels remain Standard Model(SM)-like. In other parts of the parameter space $H^{\pm \pm}$ (and $H^{\pm}$) interfere destructively, reducing the two photon branching ratio tremendously below the SM prediction. Such properties allow to account for any excess such as the one reported by ATLAS/CMS at $\approx 125$ GeV if confirmed by future data; if not, for the fact that a SM-like Higgs exclusion in the diphoton channel around 114-115 GeV as reported by ATLAS, does not contradict a SM-like Higgs at LEP(!), and at any rate, for the fact that ATLAS/CMS exclusion limits put stringent lower bounds on the $H^{\pm \pm}$ mass, particularly in the parameter space regions where the direct limits from same-sign leptonic decays of $H^{\pm \pm}$ do not apply.Comment: 26 pages, 7 figure

Associated production of SM Higgs with a photon in type-II seesaw models at the ILC

We consider the production of a single Standard Model (SM) Higgs boson ($$h^0$$) in association with a photon at the future Linear collider (LC) in the context of a type-II seesaw model. The type-II seesaw model extends the SM particle content by adding one triple Higgs where its Higgs coupling is a key parameter of the scalar potential triggering the electroweak symmetry-breaking mechanism in the SM. It is a well motivated model since it provides neutrino masses and mixing. The LC presents a particularly interesting possibility to probe Higgs couplings due to the clean beams in the initial state. We study the one loop processes $$e^+e^- \rightarrow h^0\gamma$$ and $$e^-\gamma \rightarrow e^- h^0$$, we show that it is possible to correlate the total cross section predictions with the couplings $$h^0\gamma \gamma$$ and $$h^0\gamma Z$$ which are sensitive to the presence of singly and doubly charged Higgs. For parameter points allowed by the current experimental constraints, our numerical results show that the effect of $$H^\pm$$ and $$H^{\pm \pm }$$ can be as large as ± 25% with respect to the SM predictions. For both processes, we also present differential cross section for different center of mass energy

Extended Higgs sector of 2HDM with real singlet facing LHC data

We study the phenomenology of the two Higgs doublet model with a real singlet scalar S (N2HDM). The model predicts three CP-even Higgses $$h_{1,2,3}$$, one CP-odd $$A^0$$ and a pair of charged Higgs. We discuss the consistency of the N2HDM with theoretical as well as with all available experimental data. In contrast with previous studies, we focus on the scenario where $$h_2$$ is the Standard Model (SM) 125 GeV Higgs, while $$h_1$$ is lighter than $$h_2$$ which may open a window for Higgs to Higgs decays. We perform an extensive scan into the parameter space of N2HDM of type I and explore the effect of the singlet-doublet admixture. We found that a large singlet-doublet admixture is still compatible with the recent Higgs data from LHC. Moreover, we show that $$h_1$$ could be quasi-fermiophobic and would decay dominantly into two photons. We also study in details the consistency of the non-detected decay of $$h_2\rightarrow h_1 h_1$$ with LHC data followed by $$h_1\rightarrow \gamma \gamma$$ which leads to four photons final state at LHC: $$pp\rightarrow h_2\rightarrow h_1 h_1\rightarrow 4\gamma$$. Using the results of null searches of multi-photons carried by the ATLAS collaboration, we have found that a large area of the parameter space is still allowed. We also demonstrate that various neutral Higgs of the N2HDM could have several exotic decays

Multiple pancreatic metastases from renal cell carcinoma: report of two resected cases.

In this paper are described two patients with multiple pancreatic metastases from renal cell carcinoma, and the surgical procedures that were carried out