Low scale leptogenesis and dark matter in the presence of primordial black holes

TL;DR

This paper explores how primordial black holes influence low-scale leptogenesis and dark matter production within the minimal scotogenic model, revealing conditions under which these phenomena can coexist without overproduction or dilution.

Contribution

It demonstrates that primordial black holes can serve as non-thermal sources of leptogenesis and affect dark matter abundance, expanding the viable parameter space of the scotogenic model.

Findings

PBH can induce non-thermal leptogenesis and dilute lepton asymmetry.

PBH parameters can reconcile overproduction issues in standard cosmology.

Light scalar DM is constrained to freeze out after PBH evaporation.

Abstract

We study the possibility of low scale leptogenesis along with dark matter (DM) in the presence of primordial black holes (PBH). For a common setup to study both leptogenesis and DM we consider the minimal scotogenic model which also explains light neutrino mass at radiative level. While PBH in the mass range of $0.1-10^5$ g can, in principle, affect leptogenesis, the required initial PBH fraction usually leads to overproduction of scalar doublet DM whose thermal freeze-out occurs before PBH evaporation. PBH can lead to non-thermal source of leptogenesis as well as dilution of thermally generated lepton asymmetry via entropy injection, with the latter being dominant. The parameter space of scotogenic model which leads to overproduction of baryon or lepton asymmetry in standard cosmology can be made consistent in the presence of PBH with appropriate initial mass and energy fraction. On the other hand, for such PBH parameters, the scalar DM is constrained to be in light mass regime where its freeze-out occurs after PBH evaporation. We then discuss the possibility of fermion singlet DM with $N_2$ leptogenesis in the same model where due to singlet nature of DM, its connection with PBH parameters and hence leptogenesis becomes stronger compared to the previous case.