Here it says this decay mode is a violation of C-parity. I don't understand how that works.
So $\omega$ has $C=-1$ and $J=1$ and $\pi^0$ has $C=1$ and $J=0$, that means the orbital angular momentum of final state is $L=1-0=1$. Consider C-parity of final state we get $C=(-1)^L=-1$. This seems to agree with C-parity conservation?
I've also seen an argument saying that our final state with $L=1$ is anti-symmetric if we exchange two $\pi^0$, which is forbidden since they are bosons. But I don't understand how that's related to C-parity.