Related papers: Some remarks on tree-level vacuum stability in two…
We consider the Two Higgs Doublet Model (2HDM) of type III which leads to Flavour Changing Neutral Currents (FCNC) at tree level. In the framework of this model we can use an appropriate form of the Yukawa Lagrangian that makes the type II…
We consider a two Higgs-doublet model with $S_3$ symmetry, which implies a $\pi \over 2$ rather than 0 relative phase between the vacuum expectation values $<\Phi_1>$ and $<\Phi_2>$. The corresponding Feynman rules are derived accordingly…
Extended electroweak scalar sectors containing several doublet multiplets require flavour-aligned Yukawa matrices to prevent the appearance at tree level of unwanted flavour- changing neutral-current transitions. We analyse the misalignment…
We consider a complex singlet scalar in the spectral action approach to the standard model. It is shown that there is a range of initial values at the unification scale which is able to produce Higgs and top quark masses at low energies.…
We discuss the realization of two Higgs doublets model in the framework of 6 dimensional Gauge-Higgs Unification model with a simple Lie group G_M. Two Higgs SU(2)_L doublets can emerge at the low energy effective theory, and the quartic…
The complex field $\Phi$ containing the QCD axion has a natural portal coupling to the Higgs doublet of the form $\lambda_{h \phi}|\Phi|^2 |H|^2$. Here we consider the possibility that $\lambda_{h \phi}$ has a natural magnitude for a…
We consider the conditions for the validity of a two-Higgs doublet model at high energy scales, together with all other low- and high-energy constraints. The constraints on the parameter space at low energy, including the measured value of…
A discrete symmetry between quarks and (generalized) leptons can exist in nature, and its spontaneous symmetry breaking scale can be as low as a few TeV. Such a discrete symmetry also has interesting implications for how electroweak…
We consider a 4-Higgs-doublet model in which each Higgs doublet gives mass to one of the fermion sets $\{ m_t\}$, $\{ m_b,m_\tau,m_c \}$, $\{ m_\mu,m_s \}$, and $\{ m_d,m_u,m_e \}$. The sets have the feature that within each of them the…
A two higgs doublet model with tree level natural flavor conservation can lead to P and T odd nucleon-nucleon (NN) interaction through tree level Feynman diagrams. In this article we estimate the magnitudes of the parameters that…
The stability of the Standard Model (SM) Higgs vacuum is a long-standing issue in particle physics. The SM Higgs quartic coupling parameter is expected to become negative at high scales, potentially generating an unstable vacuum well before…
We obtain tree-level unitarity constraints for the most general Two Higgs Doublet Model (2HDM) with explicit CP-violation. We briefly discuss correspondence between possible violation of tree level unitarity limitation and physical content…
We analyse the possibility of charge breaking minima developing in the Higgs triplet model, and under what conditions they are deeper than charge-preserving ones. Analytical expressions relating the depth of minima of different types are…
The data accumulated so far confirm the Higgs-like nature of the new boson discovered at the LHC. The Standard Model Higgs hypothesis is compatible with the collider results and no significant deviations from the Standard Model have been…
We present a vacuum of heterotic M-theory whose observable sector has the MSSM spectrum with the addition of one extra pair of Higgs-Higgs conjugate superfields. The quarks/leptons have a realistic mass hierarchy with a naturally light…
We discuss vacuum stability in Froggatt-Nielsen (FN) models. One concern in FN models is that for large flavon VEVs the running of the quartic Higgs coupling is enhanced what might lead to a more severe instability compared to the Standard…
Motivated by recent results from the LHC experiments, we analyze Higgs couplings in two Higgs doublet models with an approximate PQ symmetry. Models of this kind can naturally accommodate sizable modifications to Higgs decay patterns while…
We investigate the possibility of a Higgs-Higgs bound state in the two Higgs doublet model. Specifically we look for the effect of dimension six operators, generated by new physics at a scale of a few TeV, on the self-couplings of the heavy…
In this paper we study the stability problem of a tree of elastic strings with local Kelvin-Voigt damping on some of the edges. Under the compatibility condition of displacement and strain and continuity condition of damping coefficients at…
This article considers three non-zero hypercharge triplets as an extension of the Standard Model Higgs doublet. Under extra $U(1)_{L_{\mu}-L_{\tau}}$ symmetry, the triplets are charged. We examine the stability of the electroweak vacuum at…