Neutrino decoupling in standard and non-standard scenarios

Abstract

We discuss the phenomenology of neutrino decoupling in the early universe in standard and nonstandard scenarios. We review how the effective number of neutrino species in the early universe (N eff ) is calculated in the three-neutrino case, which gives Neff=3.044, and show how this result can change when one considers non-standard properties such as non-standard interactions between neutrinos and electrons and a non-unitary three-neutrino mixing matrix.