For 10 points, identify these particles which come in the "electron," "muon," and "tau" varieties, and which are known to be extremely light.
The mass matrix of these particles has an eigenvalue on the Dirac scale, and another eigenvalue on the Majorana scale; the balance between those eigenvalues explains the seesaw mechanism for their unusual properties. A sine-squared of 2 theta term and a square of mass difference term are found in the equation which predicts the probability density of their flavors; the switching of these particles between flavors is called their namesake "oscillation." They were first postulated by Wolfgang Pauli, who sought to explain the violation of energy conservation in beta decay. For 10 points, identify these particles which come in the "electron," "muon," and "tau" varieties, and which are known to be extremely light.
The mass matrix of these particles has an eigenvalue on the Dirac scale, and another eigenvalue on the Majorana scale; the balance between those eigenvalues explains the seesaw mechanism for their unusual properties.
{neutrino}