Related papers: Lepton parameters in the see-saw model extended by…
We discuss a two Higgs doublet model with extra $U(1)_X$ gauge symmetry where lepton specific (type-X) structure for Yukawa interactions is realized by charge assignment of fields under the $U(1)_X$. Extra charged leptons are introduced to…
There are some radiative origins for the neutrino masses in the conventional left-right symmetric models with the usual bi-doublet and triplet Higgs scalars. These radiative contributions could dominate over the tree-level seesaw and could…
Curiously in the minimal left right symmetric model, chiral symmetry that protects the electron's mass ($m_e$), due to parity (P), implies in the symmetry limit the vanishing of its neutrino mixing angles. We break the chiral symmetry…
Neutrino masses can be generated by fermion triplets with TeV-scale mass, that would manifest at LHC as production of two leptons together with two heavy SM vectors or higgs, giving rise to final states such as 2 leptons + 4 jets (that can…
We extend the singlet Majoron model of dark radiation by adding another singlet scalar of unit lepton charge. The spontaneous breaking of global $U(1)_L$ connects dark radiation with neutrino mass generation via the type-I seesaw mechanism.…
Lepton-flavour symmetry in the Standard Model is broken by small masses for charged leptons and neutrinos. Introducing neutrino masses via dimension-5 operators associated to lepton-number violation at a very high scale, the corresponding…
A nonuniversal abelian extension $\mathrm{U(1)}_{X}$ free from chiral anomalies is introduced into the Standard Model (SM), in order to evaluate its suitability in addressing the fermion mass hierarchy (FMH) by using seesaw mechanisms…
Small realistic Majorana neutrino masses can be generated via a Higgs triplet $(\xi^{++}, \xi^+, \xi^0)$ without having energy scales larger than $M_*={\cal O}(1)$ TeV in the theory. The large effective mass scale $\Lambda$ in the…
We analyze the renormalization group equations for the Standard Model at the one and two loops levels. At one loop level we find an exact constant of evolution built from the product of the quark masses and the gauge couplings $g_{1}$ and $…
We calculate the values and 1 sigma ranges of the running quark and lepton Yukawa couplings as well as of the quark mixing parameters at various energy scales, i.e. at M_Z, 1 TeV, 3 TeV, 10 TeV and at the GUT scale, to provide useful input…
The observation of neutrino masses leads to the possibility of leptonic mixing and CP violation. One of the simplest extensions of the Standard Model giving rise to neutrino masses consists of the introduction of one righthanded neutrino…
We examine the e-e- -> W-W- lepton number violating process in the frame of the Standard Model with additional right-handed neutrino singlets. We give results in the framework of the `see-saw' as well as other models, where there is no…
Extending the standard model with three right-handed neutrinos ($N_k$) and a second Higgs doublet ($\eta$), odd under the discrete parity symmetry $Z_2$, Majorana neutrino masses can be generated at 1-loop order. In the resulting model, the…
The present work introduces two possible extensions of the Standard Model Higgs sector. In the first case, the Zee-Babu type model for the generation of neutrino mass is augmented with a scalar triplet and additional singly charged scalar…
We propose a radiative lepton model, in which the charged lepton masses are generated at one-loop level, and the neutrino masses are induced at two-loop level. On the other hand, tau mass is derived at tree level since it is too heavy to…
Type I and type II seesaw contributions to the mass matrix of light neutrinos are inherently related if left-right symmetry is realized at high energy scales. We investigate implications of such a relation for the interpretation of neutrino…
We present theories of `Natural Neutrinos' in which neutral fermionic top partner fields are simultaneously the right-handed neutrinos (RHN), linking seemingly disparate aspects of the Standard Model structure: a) The RHN top partners are…
We propose two versions of radiative linear seesaw models, where electrically charged scalars and vector-like leptons generate the Dirac neutrino mass submatrix at one and two loop levels. In these models, the SM charged lepton masses are…
It is well-known that leptogenesis in low energy scale is difficult in the conventional Type-I seesaw mechanism with hierarchical right-handed neutrino masses. We show that in a class of two Higgs doublet model, where one Higgs doublet…
In left-right symmetric models (LRSM) the light neutrino masses arise from two sources: the seesaw mechanism and a VEV of an SU(2)$_L$ triplet. If the left-right symmetry breaking, $v_R$, is low, $v_R\lsim15\TeV$, the contributions to the…