
Since the charged pions decay into two particles, a muon and a muon neutrino, seems quarks disappeared!,
The decay proceeds by the weak interaction $W^{+}$ and can be visualized in terms of Feynman diagrams.
Isn't it why Quarks are not directly observed!?
I read somewhere:
If you are consistent thinker you can go even further and question existence of quarks themselfs then you will not have a problem with fractional charge