Puzzles in charmonium decays

Abstract

The open charm effects via intermediate hadron loop transitions seem to play a crucial role in the understanding of several existing "puzzles" in charmonium exclusive decays, such as the $\psi (3770)$ non-$D\bar{D}$ decays, and "$\rho \pi$ puzzle" etc. In the charmonium energy region, non-perturbative mechanisms could be still sizeable, and as a consequence the intermediate hadron loop transitions also provide a mechanism for the helicity-selection-rule (HSR) violation. We report our recent progress on those existing puzzles.

Comments: Invited talk on the 15th International Conference in QCD, June 28- July 3, 2010, Montpellier, France