Neutrinos and the Matter-Antimatter Asymmetry of the Universe
- Boris Kayser, Fermi National Accelerator Laboratory (FNAL)
Tuesday, April 22, 1:45 PM - NSCL/HEP Joint Seminar
Biomedical & Physical Sciences Bldg., Rm. 1400
We will review what has been learned about the neutrinos and about leptonic mixing since the discovery of neutrino oscillation. We will then describe the See-Saw picture of the origin of neutrino masses. This picture hypothesizes the existence of superheavy neutrinos, and we will explain how CP-violating decays of these superheavy neutrinos in the early universe may have given rise to the universe's observed matter-antimatter asymmetry. As we will emphasize, this explanation of the asymmetry requires that nature not conserve the Lepton Number that distinguishes antileptons from leptons, and that nature violate CP symmetry in the leptonic sector. We would establish that the first requirement is met by observing nuclear neutrinoless double beta decay, and that the second one is met by observing CP violation in neutrino oscillation. The degree to which the latter CP violation and the one in the early universe are related will be discussed.