Thermal keV neutrino dark matter in minimal gauged B-L model with cosmic
  inflation
  We investigate the possibility of keV scale thermal dark matter in a minimal
gauged $B - L$ extension of the standard model with three right-handed
neutrinos in the context of cosmic inflation. The complex singlet scalar field
responsible for the spontaneous breaking of $B-L$ gauge symmetry is
non-minimally coupled to gravity and serves the role of inflaton. The lightest
right-handed neutrino $N_1$ can be a dark matter candidate if its couplings to
leptons are sufficiently suppressed or forbidden. While keV scale $N_1$ gives
rise to the possibility of warm dark matter, its thermal production leads to
over-abundance. The subsequent entropy dilution due to heavier right-handed
neutrino decay can bring the DM abundance within the observed limit. We
constrain the model parameters from the requirement of producing sufficient
entropy dilution, inflationary observables along with other phenomenological
constraints. While these requirements cannot satisfy light neutrino data,
suitable extension of the minimal model can accommodate it.
