Chiral Sum-Rules for ${\mathcal{L}}_{(6)}^{WZ}$ Parameters and Application to ${\pi }^0,\eta ,{\eta }^{\prime }$ Decays

B. Moussallam

The chiral expansion of the low energy processes ${\pi }^0\to \gamma \gamma$ and $\eta \to \gamma \gamma$ is reconsidered with particular emphasis on the question of the evaluation of the two low-energy parameters…