Related papers: Dirac neutrinos in a $SU(2)$ left-right symmetric …
We propose a $B-L$ gauged extension of the Standard Model where light neutrino masses arise from type III seesaw mechanism. Unlike the minimal $B-L$ model with three right handed neutrinos having unit lepton number each, the model with…
We study the possibility of generating tiny Dirac masses of neutrinos in Left-Right Symmetric Model (LRSM) without requiring the existence of any additional symmetries. The charged fermions acquire masses through a universal seesaw…
We show that a version of the nearly Minimal Supersymmetric Standard Model (nMSSM), extended only in the singlet sector to include the additional superfields of right-handed neutrinos and very heavy Dirac particles conserving $B-L$, admits…
The R-symmetry formalism is applied for the supersymmetric SU(3)_C X SU(3)_L X U(1)_X (3-3-1) model with right-handed neutrinos. For this kind of models, we study generalization of the MSSM relation among R-parity, spin and matter-parity.…
In the recently proposed dark left-right gauge model (DLRM) of particle interactions, the usual left-handed lepton doublet (nu,e)_L transforming under SU(2)_L is accompanied by the UNUSUAL right-handed fermion doublet (n,e)_R transforming…
If neutrinos are truly Dirac fermions, the smallness of their masses may still be natural if certain symmetries exist beyond those of the standard model of quarks and leptons. We perform a systematic study of how this may occur at tree…
Neutrinos can have naturally small Dirac masses if the Standard Model singlet right-handed neutrinos are light composite fermions. Theories which produce light composite fermions typically generate many of them, three of which can marry the…
Recently, there has been a growing interest in extensions of the Standard Model in which naturally small Dirac neutrino masses arise due to existence of a symmetry which protects neutrino's Diracness. Motivated by this, we consider an…
Assuming all three known neutrinos are Dirac fermions, $U(1)_{B-L}$ can be an exact symmetry. We show that, if the condition of charge quantization is relaxed, the anomaly-free $B-L$ charges of two out of three right-handed neutrinos can be…
In this thesis I discuss in some detail the possibility that neutrinos are Dirac. If this is indeed the case, some extra symmetries beyond the Standard Model gauge group need to be enforced in order to protect Diracness and the smallness of…
We propose a novel SU(3)_c\times SU(2)_L\times SU(2)_R\times U(1)_{B-L} left-right symmetric model where the standard model fermion and Higgs fields are SU(2)_L doublets or SU(2) singlets while their mirror partners are SU(2)_R doublets or…
In the inverse seesaw extension of the standard model, supersymmetric or non-supersymmetric, while the light left-handed neutrinos are Majorana, the heavy right-handed neutrinos are pseudo-Dirac fermions. We show how one of these latter…
The minimally extended standard model of particle physics contains three right handed or sterile neutrinos, coupled to the active ones by a Dirac mass matrix and mutually by a Majorana mass matrix. In the pseudo-Dirac case, the Majorana…
$SU(2)_L$ triplet scalars appear in models motivated for the left-right symmetry, neutrino masses and dark matter (DM), etc.. If the triplets are the main decay products of the DM particle, and carry nonzero lepton numbers, they may decay…
We present a scenario of neutrino masses and mixing angles. Each generation includes a sterile right handed neutrino in addition to the usual left handed one. We assume a hierarchy in their Dirac masses similar to, but much larger than the…
The exchange symmetry between the muon neutrino and the tau neutrino for the neutrino mass matrix has been very useful in understanding the near maximal atmospheric neutrino mixing angle. However, this symmetry can not be imposed at the…
We propose a new model for naturally light Dirac neutrinos and explain the baryon asymmetry of the universe through neutrinogenesis. We extend the standard model with a real singlet scalar, a heavy singlet Dirac fermion and a heavy doublet…
If neutrinos have masses, why are they so tiny? Are these masses of the Dirac type or of the Majorana type? We are already familiar with the mechanism of how to obtain a tiny Majorana neutrino mass by the famous see-saw mechanism. The…
We show that, in $U(1)_R$-symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or…
An alternative left-right model of quarks and leptons, where the $SU(2)_R$ lepton doublet $(\nu,l)_R$ is replaced with $(n,l)_R$ so that $n_R$ is not the Dirac mass partner of $\nu_L$, has been known since 1987. Previous versions assumed a…