Dark Matter-Driven Low-Scale Leptogenesis via Neutrino Portal

We propose a novel framework for low-scale leptogenesis within an extension of the Standard Model (SM) that includes three SU(2) singlet right-handed neutrinos, a singlet charged neutral fermion, and a real scalar field. In this setup, the CP asymmetry arises through a rich interplay of mechanisms, including two-body decays of the lightest right-handed neutrino into leptons and Higgs or into dark-sector particles, as well as multiple 2 -> 2 scattering processes involving visible and dark states. Crucially, the CP-violating phases originate not only from conventional vertex and self-energy corrections but also from novel interference effects mediated by the dark sector, which significantly enrich the sources of asymmetry. A distinctive feature of our model is the direct connection between the dark sector and leptogenesis, providing a unified explanation for both the matter-antimatter asymmetry and DM abundance. This connection leads to enhanced CP violation in neutrino interactions and predicts new dark-sector particles accessible at the LHC.