Neutrinos are truly elusive particles: electrically neutral, very light and weakly interacting. That is why we know less about them than about other particles of the Standard Model of particle physics. The quantum-mechanical phenomena of “neutrino oscillations” have allowed us to understand much better the properties of these particles, but still there are some discrepancies between the experimental results and the commom framework in which the neutrino oscillations are studied. Could these disagreements be understood if we introduce a new, “sterile”, neutrino in our formalism? This is the question studied in this paper of the month.
So what was our starting point?
To explain what neutrino oscillations are, we need to know that neutrinos (and antineutrinos, the antiparticles of the neutrinos) come in three known types, corresponding to the three families of charged leptons and quarks in the Standard Model of elementary particles. We refer to these different types of neutrino as the electron, the muon and the tau neutrino.
