Mesons are bosons, therefore their wavefunction must be symmetric under particle exchange. Overall, the meson wave function (WF) has the following contributions:
WF=|flavor⟩|spin⟩|radial⟩|color⟩.
Mesons are a color singlet, their color wavefunction looks like: 1√3(|rˉr⟩+|bˉb⟩+|gˉg⟩)
For the pseudoscalar mesons the spin part is antisymmetric because the spins are a spin singlet.
The radial part is symmetric for the pseudoscalar/vector mesons, because the angular momentum ℓ is zero.
When it comes to the flavor part of the wavefunction for the pseudoscalar mesons, it is symmetric as well: for example π+:1√2(|uˉd⟩+|ˉdu⟩).
This gives us an overall antisymmetric wavefunction because of the antisymmetric spins. But the wavefunction has to be symmetric! The same goes for the vector mesons: there we just have an antisymmetric flavor part times symmetric spin. So it is again overall antisymmetric.
What's wrong with this reasoning?
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