Neutrino

An elementary particle belonging to the “lepton” family of particles. Neutrinos and their anti-particles, anti-neutrinos, have no charge, although measurements show that they are not massless. Neutrinos rarely interact with matter: they can fly through lightyears of lead without coming to a stop. Therefore, they cannot be detected directly by the particle detectors at the LHC: their presence has to be inferred by detecting and measuring every other particle produced in the collisions and then applying conservation laws. Neutrinos are recorded as “missing transverse energy” or MET, although MET could also be a sign of previously undiscovered, non-interacting particles.