Chiral Symmetry and Charmonium Decays to Two Pseudoscalars

We apply hard pion Chiral Perturbation Theory to charmonium decays to $\pi\pi$, $KK$ and $\eta\eta$. We first discuss why we expect to be able to provide results for the chiral logarithms in $\chi_{c0}$ and $\chi_{c2}$ decays to two pseudoscalars while for the decays from $J/\psi$, $\psi(nS)$ and $\chi_{c1}$ no simple prediction is possible. The leading chiral logarithm turns out to be absent for $\chi_{c0},\chi_{c2}\to PP$. This result is true for all fully chiral singlet states of spin zero and two.