Fermion Dark Matter with $N_2$ Leptogenesis in Minimal Scotogenic Model
  We study the possibility of singlet fermion dark matter (DM) and successful
leptogenesis in minimal scotogenic model which also provides a common origin of
DM and light neutrino masses. In this scenario, where the standard model (SM)
is extended by three gauge singlet fermions and one additional scalar doublet,
all odd under an in-built $Z_2$ symmetry, the lightest singlet fermion which
also happens to be the lightest $Z_2$ odd particle, can be either thermal or
non-thermal DM candidate depending upon the strength of its couplings with SM
leptons and the $Z_2$ odd scalar doublet. In both the scenarios, the $Z_2$ odd
scalar doublet plays a non-trivial role either by assisting coannihilation with
thermal DM or by providing a source for non-thermal DM via decay. The heavier
$Z_2$ odd singlet fermion produces a net lepton asymmetry through its
out-of-equilibrium decay into SM leptons and $Z_2$ odd scalar doublet. We show
that the requirement of producing the observed baryon asymmetry pushes the
scale of leptogenesis in case of normal ordering of light neutrino masses to
several order of magnitudes above TeV scale. In case of inverted ordering
however, it is possible to have successful $N_2$ leptogenesis at a scale of few
tens of TeV. Inclusion of lepton flavour effects lowers this scale of
leptogenesis by around an order of magnitude in both the cases. Correct DM
abundance can be realised either by thermal freeze-out or by freeze-in
mechanism in different parts of the parameter space that can have interesting
prospects for ongoing experiments.
