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We study the Peccei-Quinn (PQ) symmetry of sterile right-handed neutrino sector and the gauge symmetries of the Standard Model (SM). Due to four-fermion interactions, spontaneous breaking of these symmetries at the electroweak scale generates top-quark Dirac mass and sterile neutrino Majorana mass. The top quark channels yields massive Higgs, $W^pm$ and $Z^0$ bosons. The sterile neutrino channel yields the heaviest sterile neutrino Majorana mass, sterile Nambu-Goldstone axion (or majoron) and massive scalar $chi$boson ($m_chisim 10^2$ GeV). Their tiny couplings to SM particles are effectively induced by four-fermion operators. We show that such sterile axion is the PQ solution to the strong CP problem. The lightest sterile neutrino ($m_N^esim 10^2$ keV), sterile QCD axion ($m_a< 10^{-6}$ eV, $g_{agamma}< 10^{-13} {rm GeV}^{-1}$) and $chi$boson can be dark matter particle candidates, for their tiny couplings and long lifetimes inferred from the Xenon1T experiment. The axion and $chi$boson couplings to SM particles are below the values reached by current laboratory experiments and astrophysical observations for directly or indirectly detecting dark matter particles.
We consider extensions of the Standard Model in which a spontaneously broken global chiral Peccei-Quinn (PQ) symmetry arises as an accidental symmetry of an exact $Z_N$ symmetry. For $N = 9$ or $10$, this symmetry can protect the accion - the Nambu-G
We show that, for values of the axion decay constant parametrically close to the GUT scale, the Peccei-Quinn phase transition may naturally occur during warm inflation. This results from interactions between the Peccei-Quinn scalar field and the ambi
We propose a model where Dirac neutrino mass is obtained from small vacuum expectation value (VEV) of neutrino-specific Higgs doublet without fine-tuning problem. The small VEV results from a seesaw-like formula with the high energy scale identified
Extending the Standard Model with three right-handed neutrinos and a simple QCD axion sector can account for neutrino oscillations, dark matter and baryon asymmetry; at the same time, it solves the strong CP problem, stabilizes the electroweak vacuum
We review sterile neutrinos as possible Dark Matter candidates. After a short summary on the role of neutrinos in cosmology and particle physics, we give a comprehensive overview of the current status of the research on sterile neutrino Dark Matter.