Publications (81) View all
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Article: Higgs boson decay into 2 photons in the type~II Seesaw Model
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ABSTRACT: 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.Journal of High Energy Physics 04/2012; 1204:136. · 5.83 Impact Factor -
Article: h \gamma \gamma Coupling in Higgs Triplet Model
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ABSTRACT: 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 $H^{\pm\pm}$.02/2012; -
Article: The Higgs Potential in the Type II Seesaw Model
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ABSTRACT: 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.Physical Review D 05/2011; 84:095005. · 4.56 Impact Factor -
Article: CP violation in charged Higgs production and decays in the Complex Two Higgs Doublet Model
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ABSTRACT: We study the effects of CP violation in charged Higgs boson production $pp\to t H^\pm + X$ at the LHC, as well as in the charged Higgs boson decays $H^\pm \to t b$ and $H^\pm \to W^\pm H_i^0$, $i=1,2,3$. The study is done in the framework of the type II complex Two Higgs Doublet Model (2HDM) with softly broken $Z_2$ symmetry. In this model violation of CP invariance is induced by the complex parameter $m^2_{12}$ of the tree-level Higgs potential. We calculate the CP violating rate asymmetries for $H^+$ and $H^-$ production and decays as well as for the combined processes at one-loop level and perform a detailed numerical analysis. All calculations are done with the automatic amplitude generator FeynArts and the calculational tool FormCalc, for which we have written a complete complex 2HDM model file and relevant fortran drivers. The implementation of the complex 2HDM in FeynArts and FormCalc is described. In comparison with the analogous results in the MSSM, all considered CP violating asymmetries are smaller by an order of magnitude and do not exceed 2 to 3%.11/2010; -
Article: Charged Higgs bosons in the next-to MSSM (NMSSM)
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ABSTRACT: The charged Higgs boson decays H±→W±A1 and H±→W±Hi are studied in the framework of the next-to-minimal supersymmetric standard model (NMSSM). It is found that the decay rate for H±→W±A1 can exceed the rates for the τ±ν and tb channels both below and above the top–bottom threshold. The dominance of H±→W±A1 is most readily achieved when A1 has a large doublet component and small mass. We also study the production process pp→H±A1 at the LHC followed by the decay H±→W±A1, which leads to the signature W±A1A1. We suggest that pp→H±A1 is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate tanβ and dominant decay mode H±→W±A1. This W±A1A1 signature can also arise from the Higgsstrahlung process pp→W±H1 followed by the decay H1→A1A1. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods.European Physical Journal C 05/2008; 55(4):653-665. · 3.63 Impact Factor
