Research
Neutrino are the second-most abundant particle in the universe but the least known among those in the Standard Model because they can interact only weakly.
After their discovery in 1956 and the detection of all the three neutrino flavours in the following decades, in 1998, the Super-K experiment observed that neutrinos oscillate. This is a quantum interference process, predicted in 1957 by Bruno Pontecorvo, that implies that at least 2 out of the 3 neutrinos are massive. Hence, an update of the Standard Model is necessary.
Since then, there remain only two parameters of the neutrino oscillation probability that need to be measured: (1) which one of the three nown states is the heaviest (mass ordering); (2) a complex phase that could make flavour oscillations different for neutrinos and antineutrinos and, thus, violate the charge-parity (CP) symmetry in the leptonic sector. Such violation would be a necessary ingredient for understanding the origin of the matter dominance in the universe.
The best way to search for leptonic CP violation and determine the neutrino mass ordering is to precisely measure neutrino oscillations at the long-baseline experiments.