Related papers: The hierarchy problem and the vacuum stability in …
We study the $S3$ symmetric extension of the Standard Model in which all the irreducible representations of the permutation group are occupied by $SU(2)$ scalar doublets, one of which is taken as inert and can lead to dark matter…
Many models have recently been proposed in which dark matter (DM) couples to Standard Model fields via a GeV-scale dark sector. We consider scenarios of this type where the DM mass, at the electroweak/TeV scale, is generated by the VEV of a…
Although the seesaw mechanism is a natural explanation for the small neutrino masses, there are cases when the Majorana mass terms for the right-handed neutrinos are not allowed due to symmetry. In that case, if neutrino-specific Higgs…
We study the phenomenology of the Standard Model (SM) Higgs sector extended by two singlet scalars. The model predicts two CP-even scalars $h_{1,2}$ which are a mixture of doublet and singlet components as well as a pure singlet scalar…
We construct a minimal viable extension of the standard model (SM) with classical scale symmetry. Its scalar sector contains a complex singlet in addition to the SM Higgs doublet. The scale-invariant and CP-symmetric Higgs potential…
We argue that adding gauge-singlet real scalars to the Standard Model can both ameliorate the little hierarchy problem and provide a realistic source of Dark Matter. Masses of the scalars should be in the 1-3 TeV range, while the lowest…
The Standard Model Higgs suffers from the hierarchy problem, typically implying new states within the reach of the LHC. If the Higgs is very heavy (~500 GeV) the states that cutoff the quadratic divergence may be beyond the reach of the…
We explore a simple model containing two singlet scalars as dark matter supplemented with a vector-like lepton. Evading collider and dark matter constraints, the model is able to accommodate the correct dark matter relic abundance and the…
Many theories require augmenting the Standard Model with additional scalar fields with large order one couplings. We present a new solution to the hierarchy problem for these scalar fields. We explore parity- and $\mathbb{Z}_2$-symmetric…
The confirmation of the Higgs boson in Run I data at the Large Hadron Collider (LHC) and the excesses in recent Run II data suggest scenarios beyond the Standard Model (SM). We pursue a study in a minimal model which is an extension of a…
The Standard Model (SM) without the Higgs mass term is scale invariant. Gildener and Weinberg generalized the scale invariant standard model (SISM) by including the multiplication of scalars in quartic forms. They pointed out that along the…
We consider an extension of the Standard Model by three singlet fermions and one singlet real scalar field. The scalar is an ultralight dark matter candidate whose abundance is set by dynamically induced misalignment from the Higgs portal.…
We discuss the constraints and phenomenology of the $Z_2 \times Z_2$ three Higgs doublet model (3HDM) with two inert scalars, originating two dark matter (DM) particles. We elucidate the competing vacua and we submit the model to all…
We study a fermionic dark matter model in which the interaction of the dark and visible sectors is mediated by Higgs portal type couplings. Specifically, we consider the mixing of a dark sector scalar with the scalars of a Two Higgs Doublet…
We consider a two-Higgs doublet scenario containing three $SU(2)_L$ singlet heavy neutrinos with Majorana masses. The second scalar doublet as well as the neutrinos are odd under a $Z_2$ symmetry. This scenario not only generates Majorana…
We propose a simple extension of the Standard Model (SM) which has a viable dark matter (DM) candidate, as well as can explain the generation of tiny neutrino masses. The DM is an electroweak (EW) singlet scalar $S$, odd under an imposed…
We argue that the Standard Model (SM) in the Higgs phase does not suffer from a "hierarchy problem" and that similarly the "cosmological constant problem" resolves itself if we understand the SM as a low energy effective theory emerging…
We propose an extension to the standard model incorporating a dark sector with a non-Abelian SU(2) gauge symmetry. The model yields stable dark matter candidates, protected by a residual $Z_3$ symmetry arising after the spontaneous symmetry…
Gauge singlet extensions of the Standard Model (SM) scalar sector may help remedy its theoretical and phenomenological shortcomings while solving outstanding problems in cosmology. Depending on the symmetries of the scalar potential, such…
We present a study of singlet-doublet vector-like leptonic dark matter (DM) in the framework of two Higgs doublet model (2HDM), where the dark sector is comprised of one doublet and one singlet vectorlike fermions (VLFs). The DM, that…