ABSTRACT
Neutrino physics has experienced quite a massive boost in recent years with the establishment of a nonvanishing rest mass of the neutrino. This allows for a variety of new features of neutrinos and has an impact on various physics processes. As discussed in more detail in the corresponding chapters, all evidence stems from neutrino oscillation searches. There are two convincing pieces of evidence:
• A deficit in upward-going muons produced by atmospheric neutrinos. This has been confirmed by long-baseline accelerator experiments. This can be explained by νμ oscillations with Δm2 ≈ 2.3 × 10−3 eV2 and sin2 2θ ≈ 1 very likely into ντ .
