# Neutrino Physics: Phenomenology and Theory

### Abstract:

The formalism of neutrino oscillation including quantum mechanical aspects is discussed. The experimental data including solar, atmospheric, reactor and accelerator long baseline experiments is reviewed, open questions and future projects are outlined. Since the results show without doubt that neutrinos have mass, the Standard Model must be extended. We discuss Dirac and Majorana masses, and in particular the various seesaw mechanisms and their phenomenological consequences. Other scenarios to generate neutrino mass are also mentioned.

Neutrinoless double beta decay caused by Majorana neutrino exchange is the main possibility to distinguish Dirac and Majorana masses. The process is discussed in detail, including experimental and nuclear physics aspects. Various alternative mechanisms beside Majorana neutrino exchange exist, for instance in left-right symmetric models, and can be tested e.g. at the LHC.

Lepton mixing turns out to be fundamentally different from quark mixing, and flavor symmetries based mostly on discrete non-Abelian symmetry groups are the main approach to explain this puzzling fact. Mathematical details of such groups are discussed and the the general structure of models is explained. Finally, non-standard physics such as light sterile neutrinos, non-standard interactions, long-range forces etc. are discussed.