Related papers: $U(1)_\chi$ and Seesaw Dirac Neutrinos
The standard model of quarks and leptons is extended to include the gauge symmetry $U(1)_\chi$ which comes from $SO(10) \to SU(5) \times U(1)_\chi$. The radiative generation of Dirac neutrino masses through dark matter is discussed in two…
A simple and elegant mechanism is proposed to resolve the problem of having a light scalar mediator for self-interacting dark matter and the resulting disruption to the cosmic microwave background (CMB) at late times by the former's…
Lepton number is promoted to an $U(1)_L$ gauge symmetry in a simple extension of the standard model. The spontaneous breaking of $U(1)_L$ by three units allows a conserved $Z_3^L$ lepton symmetry to remain, guaranteeing that neutrinos are…
Using the particle content of the fundamental {27} supermultiplet of E_6, naturally small Dirac neutrino masses are obtained in the context of SU(3)_C times SU(2)_L times U(1)_Y times U(1)_{chi}, where U(1)_{chi} comes from the…
It has recently been pointed out that the underlying symmetry of dark matter may well be $U(1)_\chi$ (coming from $SO(10) \to SU(5) \times U(1)_\chi$) with the dark parity of any given particle determined by $(-1)^{Q_\chi+2j}$, where…
In the context of $SU(3)_C \times SU(2)_L \times U(1)_Y \times U(1)_\chi$, where $U(1)_\chi$ comes from $SO(10) \to SU(5) \times U(1)_\chi$, supplemented by the non-Abelian discrete $\Delta(27)$ symmetry for three lepton families, Dirac…
Choosing how gauge $U(1)_\chi$ breaks in the context of $SO(10) \to SU(5) \times U(1)_\chi$, $Z_4$ lepton number may be obtained which maintains neutrinos as Dirac fermions. Choosing $\Delta(27)$ as the family symmetry of leptons,…
The $SU(3)_c^{}\times SU(2)_L^{} \times U(1)_Y^{}$ standard model is extended by a $U(1)_{B-L}^{}$ gauge symmetry with four right-handed neutrinos. Because of their Yukawa couplings to a Higgs singlet for spontaneously breaking the…
A new solution is presented where the right-handed neutrino $\nu_R$ in $SO(10)$ pairs up with $\nu_L$ to form a naturally light Dirac neutrino. It is based on the framework of $E_6 \to SO(10) \times U(1)_\psi$, then $SO(10) \to SU(5) \times…
The notion of U(1) lepton number (which may only be softly broken) is applied to models of dark matter which interacts with leptons. Previous scotogenic models of Majorana or Dirac neutrino mass are shown to be derivable in this framework…
I suggest a new extension of the standard model of particle physics, which introduces a dark sector with the $SU(2)_{D}\otimes U(1)_{D'}$ symmetry besides the SM sector. The new particles of the model all inhabit in the dark sector. The…
We propose the first scotogenic neutrino mass model with gauged lepton number $U(1)_L$, which is spontaneously broken by three units $\Delta L=3$ down to a residual discrete gauge symmetry $\mathbb{Z}_6$. The latter guarantees that…
The family of Dirac Seesaw models offers an intriguing alternative explanation for the smallness of neutrino masses without necessarily requiring microscopic lepton number violation, when compared to the more familiar class of Majorana…
We explore a new origin of neutrino dark energy and baryon asymmetry in the universe. The neutrinos acquire small masses through the Dirac seesaw mechanism. The pseudo-Nambu-Goldstone boson associated with neutrino mass-generation provides…
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…
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…
A known mechanism for obtaining naturally light Dirac neutrinos is implemented in the context of $SU(6) \to SU(5) \times U(1)_N$.
We attempt to understand the baryon-dark-matter coincidence problem within the quark seesaw extension of the standard model where parity invariance is used to solve the strong CP problem. The $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ gauge…
We study neutrino and dark matter based on a gauged $U(1)_R$ symmetry in a framework of radiative seesaw scenario. Identifying dark matter as a bosoninc particle, it interacts with quark and lepton sectors through vector-like heavier quark…
We propose an SO(10) \times SO(10)' model to simultaneously realize a seesaw for Dirac neutrino masses and a leptogenesis for ordinary and dark matter-antimatter asymmetries. A (16\times \overline{16}')_H scalar crossing the SO(10) and…