Related papers: Tree-level unitarity constraints in the most gener…
Tree-level accidental symmetries are known to play a fundamental role in the phenomenology of the Standard Model (SM) for electroweak interactions. So far, no significant deviations from the theory have been observed in precision, flavour…
We briefly survey several typical CP-conserving two-Higgs-doublet models (2HDMs) in light of current experiments. First we derive the masses and couplings of the mass eigenstates from the Lagrangians. Then we analyze the constraints from…
We numerically estimate a scale $\Lambda_{uni}$ at which tree-level unitarity is violated in the $SO(5)\times U(1)_X$ gauge-Higgs unification model by evaluating amplitudes for scattering of the longitudinal W bosons. The scattering…
In these proceedings we review the flavour phenomenology of two-Higgs-doublet models (2HDMs) and connect the results to the decoupling limit of the MSSM. We first study the impact of FCNC constraints on the allowed parameter space of the…
We examine perturbatively the two-Higgs-doublet extension of the \SM\ in the context of the suspected triviality of theories with fundamental scalars. Requiring the model to define a consistent effective theory for scales below a cutoff of…
The two-Higgs-doublet model provides a simple, yet interesting, generalization of the SM Higgs sector. We study the CP-conserving version of this model with general, flavor-diagonal, Yukawa couplings. Indirect constraints are obtained from…
Extra Higgs states appear in various scenarios beyond the current Standard Model of elementary particles. If discovered at the LHC or future colliders, the question will arise whether CP is violated or conserved in the extended scalar…
We discuss theoretical and phenomenological aspects of two-Higgs-doublet extensions of the Standard Model. In general, these extensions have scalar mediated flavour changing neutral currents which are strongly constrained by experiment.…
In the two-Higgs-Doublet model the alignment of the Yukawa flavour matrices of the two scalar doublets guarantees the absence of tree-level flavour-changing neutral couplings. The resulting fermion-scalar interactions are parameterized in…
We investigate the general two Higgs doublet model imposing both the unitarity conditions and the bounded-from-below conditions. Both types of conditions restrict the ranges of the parameters of the scalar potential. We study the model in…
We impose partial-wave unitarity on $2 \to 2$ tree-level scattering processes to derive constraints on the dimensions of large scalar and fermionic multiplets of arbitrary gauge groups. We apply our results to scalar and fermionic…
In Quantum Field Theory models of electro-weak interactions with spontaneously broken gauge invariance, renormalizability limits to four the degree of the Higgs potential, whose minima determine the possible vacuum states in tree…
The complex two-Higgs doublet model (C2HDM) is one of the simplest extensions of the Standard Model with a source of CP-violation in the scalar sector. It has a $\mathbb{Z}_2$ symmetry, softly broken by a complex coefficient. There are four…
We study how the requirement of perturbative unitarity restricts the parameter space of the two-Higgs-doublet model (2HDM) when higher-dimensional operators up to dimension six are included. We demonstrate that such operators can enhance…
We study the perturbative unitarity bound given by higher dimensional bosonic operators up to dim-6 for the two-Higgs-doublet model (2HDM). They lead to new physics beyond the Standard Model. We point out that such operators can lead to a…
Minimal extensions of the Standard Model (SM), such as the so-called Two Higgs Doublet Model (2HDM), can possess several accidental discrete symmetries whose spontaneous breakdown in the early universe usually lead to the formation of…
The observed light neutrinos may be related to the existence of new heavy neutrinos in the spectrum of the SM. If a pair of heavy neutrinos has nearly degenerate masses, then CP violation from the interference between tree-level and…
Appreciable CP Asymmetries (~ 10%) can arise in the reaction e+ e- -> t bar-t Z already at TREE-LEVEL in models with two Higgs doublets. For a neutral Higgs particle, h, with a mass in the range 50 GeV < m_h < 400 GeV, it may be possible to…
We established the allowed parameters of two-Higgs doublet model(2HDM) from flavor physics observables, precisely from rare $B$ meson decays. In our analysis most formidable constraints on the 2HDM parameters arise from the branching ratio…
We discuss phenomenological consequences of requiring the cancellation of one-loop quadratic divergences in corrections to scalar masses within Two-Higgs-Doublet Models (2HDM). It is shown that the Inert Doublet Model (IDM) can not…