The Lambda CDM-model in quantum field theory on curved spacetime and Dark Radiation

Understand

In the standard model of cosmology, the universe is described by a Robertson-Walker spacetime, while its matter/energy content is modeled by a perfect fluid with three components corresponding to matter/dust, radiation and a cosmological constant.

• On the other hand, in particle physics matter and radiation are described in terms of quantum field theory on Minkowski spacetime.
• We unify these seemingly different theoretical frameworks by analysing the standard model of cosmology from first principles within quantum field theory on curved spacetime: assuming that the universe is homogeneous and isotropic on large scales, we specify a class of quantum states whose expectation value of the energy density is qualitatively and quantitatively of the standard perfect fluid form up to potential corrections.
• Qualitatively, these corrections depend on new parameters not present in the standard Lambda CDM-model and can account for e.g.