A study of the Okubo-Zweig-Iizuka rule violations in $\eta_c\to VV$
  We discuss the Okubo-Zweig-Iizuka (OZI) rule violation effects in $\eta_c\to VV$ in light of the new data from BES Collaboration. In particular, a possible non-vanishing branching ratio for $\eta_c\to \omega\phi$ provides a hint of the degrees of OZI violations based on a recent factorization proposed for charmonium hadronic decays. The violation mechanism is studied via an intermediate meson exchange model. The results are consistent with the experimental observations. 
Qiang Zhao