Neutrino physics

In this lecture, I start with presenting the history of the neutrino from its invention to what we have discovered about its properties till now. I explain how we can observe neutrinos produced both naturally and artificially. Naturally produced neutrinos come to the Earth from the Sun, supernovae, collisions of cosmic rays with nuclei in the atmosphere, natural radioactivity, etc. On the other hand, those produced in accelerators and nuclear reactors are the examples of artificial neutrinos. I also illustrate what neutrino oscillations are and how such phenomena could be observed from various experiments to detect neutrinos produced in the aforementioned ways. Thanks to the discovery of neutrino oscillations, we are forced to modify the Standard Model, so as to accommodate the masses of neutrinos and lepton flavor mixing, which are essential to make neutrino flavor change. In fact, neutrinos can come in three different flavors, electron, muon and tau, and can change from one flavor to another. The origin of the tiny neutrino masses is still unknown, although we now know a few nice mechanisms capable of generating them. The generation of neutrino masses signifies physics beyond the Standard Model and can, therefore, be related to some of the unresolved fundamental issues, such as the origin of flavors, the unification of forces, the matter-antimatter asymmetry, etc. Some physicists believe that CP violation in neutrinos may be a missing piece in the understanding of the origin of the matter-antimatter asymmetry. I pedagogically explain how we can probe CP violation through neutrino oscillation experiments.