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.
Table:
The leptons
(particles with only weak and sometimes electromagnetic interactions).
All leptons have spin 
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.