and 
.
Each type experiences gravity, the electroweak interaction
and apparently nothing else.
The leptons make a short list and are easy to classify
by the three known "flavours" -- e, and .
Each type experiences gravity, the electroweak interaction
and apparently nothing else.
and are therefore
fermions. Each "generation" of lepton has its own distinctive
"flavour" (electron, muon, tau) and is governed by
its own conserved "lepton number."
For each particle there corresponds an antiparticle
of the same mass and spin but with opposite values of
electric charge and lepton number of the corresponding flavour.
