The Properties of Neutrinos

Abstract

This chapter deals with the physics of neutrinos, which are neutral particles, partners of the charged leptons in SU(2) multiplets, subject to the weak interaction only—besides their negligible gravitational interaction. Due to their low interaction probability, they are very difficult to detect and as a consequence the neutrino sector is the least known in the standard model of particle physics. In the late 1990s it has been discovered that neutrinos of different flavors (electron, muon, or tau) “oscillate”: neutrinos created with well-defined leptonic flavor may be detected in another flavor eigenstate. This phenomenon implies that neutrinos have a non-zero—although tiny even for the standards of particle physics—mass.