Neutrino Mass and Mixing

Neutrinos are a unique probe of many aspects of physics, geophysics, and astrophysics on scales ranging from 10⁻³³ to 10⁺²⁸ cm. Neutrino scattering and decays involving neutrinos have been essential in establishing the Fermi theory and parity violation, determining the elements of the CKM matrix, and testing the weak neutral current predictions of the standard model, and therefore played a significant role in the precision electroweak program as described in Section 8.3.6. Deep inelastic scattering involving neutrinos and charged leptons has also been critical in establishing the existence and properties of quarks, the structure of the nucleon, and the predictions of the short distance behavior of QCD. Similarly, neutrinos are important for the physics and/or probes of the Sun, Earth, stars, core-collapse supernovae, the origins of cosmic rays, the large scale structure of the universe, big bang nucleosynthesis, and possibly baryogenesis.