Chiral expansion of the $\pi^0\rightarrow\gamma\gamma$ decay width
  A chiral field theory of mesons has been applied to study the contribution of the current quark masses to the $\pi^0\rightarrow\gamma\gamma$ decay width at the next leading order. $2\%$ enhancement has been predicted and there is no new parameter. 
Bing An Li (Unversity of Kentucky)
hep-ph