= G parity
{c}
{title2=$G=\mathcal C e^{-i\pi J_2}$}
{wiki}
The product of <charge conjugation> and a half-turn in <isospin> is G parity. Both conjugations act on the <isospin> generators by $(J_1,J_2,J_3)\mapsto(-J_1,J_2,-J_3)$, so their product commutes with every generator. The <Schur lemma> therefore gives a common G-parity value throughout each irreducible <isospin> multiplet on which the operator acts internally. It can classify a charged multiplet even though individual charged states are not eigenstates of <charge conjugation>.
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