Quantum Kinetic Equations and neutrinos in the primordial plasma
Neutrinos are perhaps the most mysterious and elusive of the known particles, and yet play a crucial role in the early universe. In particular, neutrinos influenced the dynamical evaluation of the universe in the radiation dominated era and they contributed to set the neutron-to-proton ratio, which is a key quantity for the Big Bang Nucleosynthesis. During the seminar I will talk about different phenomena involving neutrino oscillations and I will present my past work, in which I investigated neutrino oscillations in the neutrino decoupling era. I found a series of different neutrino evolutions depending on how much lepton asymmetry one takes into account, within the current upper bound provided from relic abundances of helium-4.