Related papers: The Multiple Point Principle and Higgs Bosons
One of the simplest extensions of the Standard Model (SM) consists in adding a scalar singlet. This second Higgs boson is able to solve several fundamental problems of SM. Additional scalar particles arise naturally in composite Higgs…
Recently, ATLAS and CMS experiments at the LHC put on light the relevant results in the measurement precision of the Higgs and BSM. In such a report, where the resonance direct search was made in the $\gamma Z$ channel, a mass adjustment…
In this thesis, we investigate several aspects of models with a multiplicity of Higgs bosons. We start by focusing on models with two Higgs doublets. We claim that one of the most used models in the literature -- the so-called real…
The quadratic divergences of the Higgs mass may be cancelled either accidentally or by the exchange of some new particles. Alternatively its impact on naturalness may be weakened by raising the Higgs mass, which requires changing the…
In type II seesaw utilized to explain the observed neutrino masses and mixings, one extends the Standard Model (SM) by introducing scalar fields which transform as a triplet under the electroweak gauge symmetry. New scalar couplings…
The discovery of the Higgs by ATLAS and CMS at the LHC not only provided the last missing building block of the electroweak Standard Model, the mass of the Higgs has been found to have a very peculiar value about 126 GeV, which is such that…
Within the Constrained Minimal Supersymmetric Standard Model it is possible to predict the low energy gauge couplings and masses of the 3. generation particles from a few parameters at the GUT scale. In addition the MSSM predicts…
We study the complete one loop contribution to H^\pm\to W^\pm V, V= Z, \gamma, both in the Minimal Supersymmetric Standard Model (MSSM) and in the Two Higgs Doublet Model (2HDM). We evaluate the MSSM contributions and compare them with the…
In the alignment limit of a multi-doublet Higgs sector, one of the Higgs mass eigenstates aligns in field space with the direction of the scalar field vacuum expectation values, and its couplings approach those of the Standard Model (SM)…
We consider a version of special relativity assuming that the metric in inertial frames is conformally pseudoeuclidean and depends on some scalar field with zero vacuum average. Applying this modified special relativity to the theory of…
In the Minimal Supersymmetric Standard Model (MSSM), the masses of the charged Higgs boson ($H^\pm$) and the CP-odd scalar ($A$) are related by $M_{H^+}^2=M_A^2+m_W^2$. Furthermore, because the coupling of $W^-$-$A$-$H^+$ is fixed by gauge…
Diagrammatic two-loop results are presented for the leading QCD corrections to the masses of the neutral CP-even Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM). The results are valid for arbitrary values of the parameters…
The fine-tuning principles are examined to predict the top-quark and Higgs-boson masses. The modification of the Veltman condition based on the compensation of vacuum energies is developed. It is implemented in the Standard Model and in its…
We consider two Higgs doublet models (THDMs) with both the Higgs potential and Yukawa interactions being aligned, which we call "double-aligned THDMs". In this scenario, coupling constants of the discovered Higgs boson to the Standard Model…
A compact approximation formula for the mass of the lightest neutral CP-even Higgs boson, m_h, in the Minimal Supersymmetric Standard Model (MSSM) is derived from the diagrammatic two-loop result for m_h up to O(alpha alpha_s). By…
We discuss the realization of a vanishing effective Higgs potential at the Planck scale, which is required by the multiple-point criticality principle (MPCP), in the standard model with singlet scalar dark matter and a right-handed…
Weak-scale supersymmetry is a well motivated, if speculative, theory beyond the Standard Model of particle physics. It solves the thorny issue of the Higgs mass, namely: how can it be stable to quantum corrections, when they are expected to…
We discuss quantum corrections of new physics to the triple coupling of the lightest CP-even Higgs boson in the Two Higgs Doublet Model (THDM) and also in the Minimal Supersymmetric Standard Model (MSSM). In the THDM, quartic contributions…
A thorough analysis of stability and perturbativity bounds is performed in several versions of the two-Higgs doublet model, for both CP-conserving and spontaneously broken CP minima. LEP results further aid in establishing very strict…
We study the conditions required to make the 2HDM scalar potential stable up to the Planck scale. The lightest CP-even scalar is assumed to have been found at the LHC and the {\em alignment limit} is imposed in view of the LHC Higgs data.…