Important because there is a huge effort underway to study the connections among neutrinos, and long awaited because the tau lepton was discovered 25 years ago, and it is high time the other shoe was dropped.
WIMPS. The more massive members of each lepton pair are the electrically charged electron (the outer constituent of atoms) and two other particles that resemble electrons in all measurable ways except that they are heavier, and are unstable in today's modern universe.