The Universe at the MeV era: neutrino evolution and cosmological observables

Understand

Neutrino physics in the early Universe is key to our understanding of later cosmological stages, such as primordial nucleosynthesis (BBN) or the formation of large-scale structures.

• The coming decade promises new experimental results to explore and constrain cosmological models even more precisely - which requires robust theoretical predictions.
• This PhD thesis presents a study of the evolution of neutrinos in the first seconds after the Big Bang, more precisely when the temperature of the Universe is of the order of one mega-electronvolt.
• This evolution is obtained numerically by solving kinetic equations for which we propose a new derivation.