Related papers: Dirac neutrinos in a $SU(2)$ left-right symmetric …
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu=0 for…
We extend the visible content of the standard model (SM) with a hidden sector composed of three right-handed singlet neutrinos and one singlet Higgs. These extra singlets are charged under a new U(1)_X gauge symmetry while the SM particles…
If neutrinos are Dirac particles, their right-handed partners must be present in the theory. Once introduced in the Standard Model (SM), the difference between the baryon number $B$ and the lepton number $L$ can be promoted to a local…
We point out that a class of non-supersymmetric models based on the gauge group $SU(3)_C \times SU(2)_L\times SU(2)_R\times U(1)_{Y_L}\times U(1)_{Y_R}$ possesses an automatic, exact $Z_{2 }$ symmetry under which the fermions in the…
We examine simple extension of the standard model with a pair of fermions, one singlet and a doublet, in a common thread linking the dark matter problem with the smallness of neutrino masses associated with several exciting features. In the…
We consider a left-right symmetric extension of the Standard Model where the spontaneous breakdown of the left-right symmetry is triggered by doublets. The electroweak $\rho$ parameter is protected from large corrections in this Doublet…
The standard model left-handed neutrinos and several right-handed neutrinos can obtain a tiny Dirac mass matrix through their mixings with relatively heavy Dirac fermions. In this Dirac seesaw scenario, the mixings involving the left-handed…
The hypothesis of an additional abelian symmetry acting in a different way on the three families of leptons leads to interesting predictions in the neutrino sector. Contrary to what happens in most seesaw models, the structures of the Dirac…
We propose that all light fermionic degrees of freedom, including the Standard Model (SM) fermions and all possible light beyond-the-standard-model fields, are chiral with respect to some spontaneously broken abelian gauge symmetry.…
We consider the conventional left-right gauge extension of the standard model of quarks and leptons without a scalar bidoublet. We study systematically how one-loop radiative Dirac neutrino masses may be obtained. In addition to two…
Specific class of textures for the Dirac and Majorana mass matrices in the seesaw model leading to a pair of almost degenerate neutrinos is discussed. These textures can be obtained by imposing a horizontal $U(1)$ symmetry. A specific model…
We present a model where Majorana neutrino mass terms are forbidden by the flavor symmetry group Delta(27). Neutrinos are Dirac fermions and their masses arise in the same way as that of the charged fermions, due to very small Yukawa…
We propose an extended Left-Right symmetric model with an additional global symmetry $U(1)_X$, which after spontaneous symmetry breaking collapses to a residual subgroup $\mathbb{Z}_2$, ensuring that the light active neutrino masses are…
We consider the Affleck-Dine mechanism for leptogenesis in the minimal MSSM with Dirac or Pseudo-Dirac neutrinos. The rolling of scalars along D-flat directions generates a left-right asymmetry in the sneutrino sector, only the left part of…
The Standard Model of particle interactions is extended to include fermion doublets (n,e)_R transforming under the gauge group SU(2)_R such that n is a Dirac scotino (dark-matter fermion), with odd R parity. Based on recent CDMS data, it is…
The present work introduces new scalar and fermionic degrees of freedom to the Standard Model. While the scalar sector is augmented by a complex scalar triplet and a doubly charged scalar singlet, the fermionic sector is extended by two…
The old issue of why there are more than one family of quarks and leptons is reinvestigated with an eye towards the use of anomaly as a tool for constraining the number of families. It is found that, by assuming the existence of…
A simple scenario of long-lived dark matter is presented. Assuming lepton number $(L)$ conservation with Dirac neutrinos, the neutral component of an $SU(2)_L$ scalar triplet with $L=2$ is a suitable candidate, which decays to two…
The unifiable supersymmetric left-right model where the neutral fermion $n$ in the $SU(2)_R$ doublet $(n,e)_R$ is a dark-matter candidate, is shown to have the requisite particle content for the neutrino $\nu$ in the $SU(2)_L$ doublet…
In Neutrinophilic Two Higgs Doublet Models, Dirac neutrino masses are obtained by forbidding a Majorana mass term for the right-handed neutrinos via a symmetry. We study a variation of such models in which that symmetry is taken to be a…