Cosmology with a Master Coupling in Flipped SU(5) $\times$ U(1): The
  $\lambda_6$ Universe
  We propose a complete cosmological scenario based on a flipped SU(5) $\times$
U(1) GUT model that incorporates Starobinsky-like inflation, taking the
subsequent cosmological evolution carefully into account. A single master
coupling, $\lambda_6$, connects the singlet, GUT Higgs and matter fields,
controlling 1) inflaton decays and reheating, 2) the gravitino production rate
and therefore the non-thermal abundance of the supersymmetric cold dark matter
particle, 3) neutrino masses and 4) the baryon asymmetry of the Universe.
