Sterile neutrino portal dark matter in $$\nu $$ ν THDM

Abstract

Abstract In this paper, we propose the sterile neutrino portal dark matter in $$\nu $$ ν THDM. This model can naturally generate tiny neutrino mass with the neutrinophilic scalar doublet $$\Phi _{\nu }$$ Φ ν and sterile neutrinos N around TeV scale. Charged under a $$Z_2$$ Z 2 symmetry, one Dirac fermion singlet $$\chi $$ χ and one scalar singlet $$\phi $$ ϕ are further introduced in the dark sector. The sterile neutrinos N are the mediators between the DM and SM. Depending on the coupling strength, the DM can be either WIMP or FIMP. For the WIMP scenario, pair annihilation of DM into NN is the key channel to satisfy various bounds, which could be tested at indirect detection experiments. For the FIMP scenario, besides the direct production of DM from freeze-in mechanism, contributions from late decay of NLOP is also important. When sterile neutrinos are heavier than the dark sector, NLOP is long-lived due to tiny mixing angle between sterile and light neutrinos. Constrains from free-streaming length, CMB, BBN and neutrino experiments are considered.