Summary and outlook

Neutrino physics has experienced quite a massive boost in the last decade with the establishment of a non-vanishing rest mass of the neutrino. This allows for a variety of new features of neutrinos and has a huge impact on various physics processes. As discussed in more detail in the corresponding chapters of this book, 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 ν_μ oscillations with https://www.w3.org/1998/Math/MathML">Δm2≈2.3×10−3eV2https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315195612/f18a0118-519b-45ed-b0ef-7b8b50cd3073/content/eq2124.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> and https://www.w3.org/1998/Math/MathML">sin22θ≈1https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315195612/f18a0118-519b-45ed-b0ef-7b8b50cd3073/content/eq2125.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> into ν_τ.

The observation of active neutrinos from the Sun besides ν_e. These results from observations performed by SNO and also Borexino together with the other solar neutrino data result. This has been confirmed with a completely different method by the KamLAND experiment using nuclear power plants resulting in combined best-fit values of https://www.w3.org/1998/Math/MathML">Δm2=(7.59±0.20)×10−5eV2https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315195612/f18a0118-519b-45ed-b0ef-7b8b50cd3073/content/eq2126.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> and https://www.w3.org/1998/Math/MathML">θ≈34∘https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315195612/f18a0118-519b-45ed-b0ef-7b8b50cd3073/content/eq2127.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>. This shows clearly that matter effects are at work in the Sun and the so-called LMA solution is correct.