The Mixing of Neutrinos
摘要
The first step of particle physics beyond the SM has been to discover that neutrino have masses as all the other fermions, albeit much smaller. In case of massive neutrinos the family lepton number is violated. Neutrinos do not carry any quantum number, with the exception of the total lepton number, which is also violated in the case of Majorana neutrinos. Thus transitions (oscillations) between neutrinos which belong to different families and have different flavour become possible. The evidence for neutrino masses is based on the experimental observation of neutrino oscillations.