This may be a bit of numerology, but I'd like to be able to make a statement like "There are 17 particles in the standard model" with some logical definition of a particle.
But this statement is surprisingly difficult to make in a logically consistent way. The problem is, there are a lot of ways to count particles:
- You can say that every polarization and charge constitutes a distinct particle. This ends up being a huge number of "particles"
- You could classify by multiplets, in which case you'd get get 9 quark fields (ignoring color-charge and anti-particles), whereas I'd want 6.
- You could say something about distinct masses, but both photons and gluons are massless
- You could say something about couplings, but this makes right-handed and left handed fields distinct.
So far the best thing I've come up with is that
- "Particles" are defined as mass eigenstates
- Particles are counted as identical to anything they can be mapped onto with global symmetry transformations (i.e. color charge rotation or charge conjugation).
But I feel like this still leaves room for someone to claim this doesn't lead to a count of 17. Is there any simple rule that leads to this count without simply naming all the particles?