The standard cosmological model predicts the existence of a cosmic neutrino background (CνB) with a present density of about nν + nν̄ ≃ 110 cm per flavour, which affects big-bang nucleosynthesis (BBN), cosmic microwave background (CMB) anisotropies, and the evolution of large scale structures (LSS). We report on a precision calculation of the CνB properties including the modification introduced ...
