Related papers: Symmetries and renormalisation in two-Higgs-double…
The Next to Minimal Supersymmetric Standard Model (NMSSM) with a Higgs-singlet coupling {\lambda} close to unity, moderate tan {\beta} and stop masses below 1 TeV minimizes the fine tuning of the electroweak scale, making possible that the…
Classifying the symmetries of the scalar sector in multi-Higgs-doublet models is the main focus of this thesis. We have found certain symmetries that are always broken in models with more than two doublets, which we name "frustrated…
We update the allowed parameter space of the CP-violating 2HDM with Type II Yukawa couplings, that survives the current experimental and theoretical constraints on the model. For a representative set of allowed parameter points, we study…
We catalogue and study three-Higgs-doublet models in terms of all possible allowed symmetries (continuous and discrete, Abelian and non-Abelian), where such symmetries may be identified as flavour symmetries of quarks and leptons. We…
We present a detailed study of the Higgs sector within an extension of the Minimal Supersymmetric Standard Model that includes one Complex Higgs Triplet (MSSM+1CHT). The model spectrum includes three singly charged Higgs bosons as well as…
Beyond the Standard Model (SM) extensions usually include extended Higgs sectors. Models with singlet or doublet fields are the simplest ones that are compatible with the $\rho$ parameter constraint. The discovery of new non-SM Higgs bosons…
Two-Higgs-Doublet-Models (THDMs) are among the simplest extensions of the standard model and are intensively studied in the literature. Using on-shell parameters such as the masses of the additional scalars as input, corresponds often to…
In this work, we study the SM-like Higgs pair productions in the framework of the general CP-violating two-Higgs-doublet model. Several constraints are imposed to the model sequentially, including the SM-like Higgs boson signal fits, the…
The Higgs boson mass problem is considered in the next-to-minimal supersymmetric standard model for the case of the spontaneous CP violation. The renormalization group equations for the gauge, Yukawa and scalar coupling constants, the…
Employing the gauge-invariant formalism in the two-Higgs-doublet model (THDM) offers profound insights into the model's fundamental structure. A specific set of gauge-invariant bilinear combinations, constructed from the Higgs doublets,…
The reconstruction of the Higgs potential in the Minimal Supersymmetric Standard Model (MSSM) requires the measurement of the trilinear Higgs self-couplings. The `double Higgs production' subgroup has been investigating the possibility of…
We study the prospects for distinguishing the CP-even Higgs boson of the minimal supersymmetric extension of the Standard Model (MSSM) from the Standard Model (SM) Higgs boson by measuring its branching ratios at an e+e- linear collider.…
We study the phenomenology of the two Higgs doublet model with a real singlet scalar $S$ (2HDMS). 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 2HDMS…
Extensions of the Minimal Supersymmetric Standard Model (MSSM) with additional singlet scalar fields solve the important mu-parameter fine tuning problem of the MSSM. We compute and compare the neutral Higgs boson mass spectra, including…
A method is presented for the analysis of the scalar potential in the general Two-Higgs-Doublet Model. This allows us to give the conditions for the stability of the potential and for electroweak symmetry breaking in this model in a very…
I present comprehensive analyses of the viable parameter regions of the Standard Model of particle physics and two of its extensions: the Standard Model with four fermion generations and the Two-Higgs-Doublets model of type II. Applying…
Depending on the Higgs-boson and top-quark masses, $M_H$ and $M_t$, the effective potential of the {\bf Standard Model} can develop a non-standard minimum for values of the field much larger than the weak scale. In those cases the standard…
In the context of Composite Higgs Models we consider the realisation of an extended Higgs sector with two Higgs doublets arising as pseudo Nambu-Goldstone bosons from a $\textrm{SO}(6) \to \textrm{SO}(4) \times \textrm{SO}(2)$ breaking. The…
The idea of reduction of couplings provides a systematic procedure to search for relations among seemingly unrelated parameters of a renormalizable theory. As a consequence, such reduced theories exhibit more constrained parameter spaces.…
The search for additional Higgs particles and the exact measurements of Higgs (self-) couplings is a major goal of future collider experiments. In this paper we investigate the possible sizes of new physics signals in these searches in the…