Primordial Relics from Inflation: Dark Matter, Dark Radiation and Baryon Asymmetry.

We investigate the production of non-thermal dark matter 
particles (DM), heavy sterile neutrinos
  from the inflaton, and beyond the Standard Model free-streaming 
relativistic particles during the reheating
  era, which is preceded by a slow-roll inflationary epoch. We consider 
benchmark values for slow-roll single-field
  inflationary scenarios satisfying current bounds obtained from 
Planck-BICEP Cosmic Microwave Background (CMB)
  data. Then, for those benchmark values, we calculate the permissible 
range of the coupling between the DM
  particle and the inflaton (y_χ) and the mass of the DM particle (m_χ) 
for the production of enough DM to
  explain the total Cold Dark Matter (CDM) mass density of the present 
universe while satisfying CMB measurements
  and other cosmological bounds. For slow-roll inflation with quartic 
potential and non-minimal coupling between
  inflaton and gravity, we consider the scenario of leptogenesis via the 
decay of sterile neutrinos produced from
  the decay of inflaton, and compare the results obtained following both 
metric and Palatini theory of gravity.
  Then, we consider inflaton decay as the source of this dark radiation 
(DR), and use the CMB data from Planck-2018
  to constrain the branching fraction for the production of DR from the 
decay of inflaton, and identify the parameter
  space involving couplings and mass of the inflaton that will be within 
the reach of next-generation CMB experiments
  like spt-3g, CMB-S4, CMB-Bharat, PICO, CMB-HD, etc.