Implications of light-quark admixtures on charmonium decays into meson   pairs
  We argue that charmonium decays into meson pairs fall into two distinct classes: one that is under control of perturbative QCD and another one that is governed by a soft mechanism. We concentrate on a systematic analysis of J/Psi (Psi') decays into a light pseudoscalar and a light vector meson and eta(c) decays into a pair of light vector mesons. These processes belong to the second class and are characterized by non-conserved hadronic helicity. It is assumed that, in these cases, the charmonium state decays dominantly through a light-quark Fock component by a soft mechanism which is characteristic of OZI-rule allowed strong decays. Estimating the light-quark admixture by meson mixing, we obtain a reasonable description of the branching ratios for these processes. 
Th. Feldmann (RWTH Aachen), P. Kroll (Wuppertal Univ.)