Neutrino
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A neutrino is a fermion that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small that it was long thought to be zero. The rest mass of the neutrino... Wikipedia
B − L: −1
Composition: Elementary particle
Electric charge: 0 e
Family: Leptons, antileptons
Interactions: Weak interaction and gravitation
Mass: < 0.120 eV (< 2.14 × 10−37 kg), 95% confidence level, sum of 3 "flavours"
Particle: spin: ±+ 1 /2ħ, chirality: Left, weak isospin: + 1 /2, lepton nr.: +1, "flavour" in