No Arabic abstract
Adding a second scalar doublet (eta^+,eta^0) and three neutral singlet fermions N_{1,2,3} to the Standard Model of particle interactions with a new Z_2 symmetry, it has been shown that Re(eta^0) or Im(eta^0) is a good dark-matter candidate and seesaw neutrino masses are generated radiatively. A supersymmetric U(1) gauge extension of this new idea is proposed, which enforces the usual R parity of the Minimal Supersymmetric Standard Model, and allows this new Z_2 symmetry to emerge as a discrete remnant.
We consider an extension of the standard model (SM) with an inert Higgs doublet and three Majorana singlet fermions to address both origin and the smallness of neutrino masses and dark matter (DM) problems. In this setup, the lightest Majorana singlet fermion plays the role of DM candidate and the model parameter space can be accommodated to avoid different experimental constraints such as lepton flavor violating processes and electroweak precision tests. The neutrino mass is generated at one-loop level a la Scotogenic model and its smallness is ensured by the degeneracy between the CP-odd and CP-even scalar members of the inert doublet. Interesting signatures at both leptonic and hadronic colliders are discussed.
General Two Higgs Doublet Models (2HDM) are popular Standard Model extensions but feature flavor changing interactions and lack neutrino masses. We discuss a 2HDM where neutrino masses are generated via type I seesaw and propose an extension where neutrino masses are generated via a type II seesaw mechanism with flavor changing interactions being absent via the presence of a U(1) gauge symmetry. After considering a variety of bounds such as those rising from collider and electroweak precision we show that our proposal stands as a UV complete 2HDM with a dark photon where neutrino masses and flavor changing interactions are addressed. A possible dark matter realization is also discussed.
We investigate an interesting correlation among dark matter phenomenology, neutrino mass generation and GUT baryogenesis, based on the scotogenic model. The model contains additional right-handed neutrinos $N$ and a second Higgs doublet $Phi$, both of which are odd under an imposed $Z_2$ symmetry. The neutral component of $Phi$, i.e. the lightest of the $Z_2$-odd particles, is the dark matter candidate. Due to a Yukawa coupling involving $Phi$, $N$ and the Standard Model leptons, the lepton asymmetry is converted into the dark matter asymmetry so that a non-vanishing $B-L$ asymmetry can arise from $(B-L)$-conserving GUT baryogenesis, leading to a nonzero baryon asymmetry after the sphalerons decouple. On the other hand, $Phi$ can also generate neutrino masses radiatively. In other words, the existence of $Phi$ as the dark matter candidate resuscitates GUT baryogenesis and realizes neutrino masses.
In the Minimal Supersymmetric Standard Model (MSSM), the scalar neutrino $tilde{ u}_L$ has odd R parity, yet it has long been eliminated as a dark-matter candidate because it scatters elastically off nuclei through the $Z$ boson, yielding a cross section many orders of magnitude above the experimental limit. We show how it can be reinstated as a dark-matter candidate by splitting the masses of its real and imaginary parts in an extension of the MSSM with scalar triplets. As a result, radiative Majorana neutrino masses are also generated. In addition, decays of the scalar triplets relate the abundance of this asymmetric dark matter to the baryon asymmetry of the Universe through leptogenesis.
We propose a neutrinophilic two Higgs doublet model with hidden local $U(1)$ symmetry, where active neutrinos are Dirac type, and a fermionic DM candidate is naturally induced as a result of remnant symmetry even after the spontaneous symmetry breaking. In addition, a physical Goldstone boson is arisen as a consequence of two types of gauge singlet bosons and contributes to the DM phenomenologies as well as additional neutral gauge boson. Then we will analyze the relic density of DM within the safe range of direct detection searches, and show the allowed region of dark matter mass.