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Pion Plus Decay

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

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As you have shown how the pion decays by the "annihlation" of the two quarks through the weak interaction, what is your question exactly? – anna v Dec 2 '12 at 12:32
Quarks aren't observed because of ... someone will post about this. Like anna said, in your diagram, the quark and antiquark confined in the pion are annihilated, but that is a different thing, it is not the reason why you don't get single free quarks (except at very high temperatures). – Mitchell Porter Dec 2 '12 at 13:29
Sounds crazy but seems Quarks do not exist and Everything is made up of anti leptons and leptons. and Pion plus decay is just leptons-anti leptons decay – Neo Dec 2 '12 at 15:01
Fractional Electric Charges were not proposed by QCD, but by the quark model, which came beforehand. – Neo Dec 2 '12 at 15:04
Normally by "lepton" we mean particles that don't interact via QCD. You seem to be thinking of "integer charged quarks"? That is an old idea, but there are some (difficult) experiments which do seem to falsify it directly. Also, the fractional charges start to make sense in a unified theory like SU(5) grand unified theory. – Mitchell Porter Dec 2 '12 at 22:56

No. By the same ''argument'', electrons and positrons wouldn't be observed because positronium decays into photons.

Pions are for (anti)quarks more or less what positronium is for elec(posi)trons.

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