Their namesake (*) quantum number is preserved by the decay of a neutron, but is violated by the chiral anomaly and sphaleron processes; however, those processes do preserve the difference between these particles' quantum number and the baryon number.
The Pati-Salam grand unified theory associated the "violet" quark color with these particles. The Koide formula relates the masses of three of these particles, and the BaBar experiment tests the fact that these particles' coupling to gauge bosons and branching ratios are only dependent on their mass; that finding is their namesake universality. One method of creating a pair of these particles involves a quark and an antiquark annihilating, creating a virtual photon which then becomes a pair of these; that is the Drell-Yan process. One of these particles was discovered by using the SPEAR ring at SLAC by Martin Perl, and has a lifetime of only 2.9 times 10 to the negative 13th seconds. Their namesake (*) quantum number is preserved by the decay of a neutron, but is violated by the chiral anomaly and sphaleron processes; however, those processes do preserve the difference between these particles' quantum number and the baryon number. The mass difference between the charged and uncharged types of these particles can be understood via the seesaw mechanism. These particles include the tau, the muon, the electron, and their associated neutrinos. For 10 points, name these particles that have spin one-half and don't undergo strong interactions.
The Pati-Salam grand unified theory associated the "violet" quark color with these particles.
leptons [anti-prompt on “neutrinos”]