Lepton asymmetries from neutrino oscillations

Reasonably large relic neutrino asymmetries can be generated by active-sterile neutrino oscillations. After briefly discussing possible applications, I describe the Quantum Kinetic Equation formalism used to compute the asymmetry growth curves. I then show how the basic features of these curves can be understood on the basis of the adiabatic limit approximation in the collision dominated epoch, and the pure MSW effect at lower temperatures.