1. Symposium on the “12% rule” and “ puzzle”
-- A brief summary of questions
Mar. 20, 2011, Beijing

2. For discussions
What mechanism leads to large helicity-selection-rule violating decays of J/  VP, especially to ?
How reliable is the 12% rule?
Are there generalities for other HSL-violating processes?
(3770)
Also, charmonium decays into baryon pairs.

3. Branching ratios for J/ (cc)  V P

4. 5. J/ enhanced? ’ suppressed? Or both?
4. How to understand the correlation between the HSL-violation and OZI-rule violation?
5. J/ enhanced? ’ suppressed? Or both? D g  V c c D*
J/, '
J/ ()  c c* P D
OZI-evading: non-pQCD dominant
Hidden charm of  meson?
Glueball component of J/?
Meson loops?
Higher Fock states? ……

5. 6. How to single out the contributions from the EM and strong transitions?
J/,  PP for the role played by EM annihilations (X.Q. Li; Yuan et al. )
c, c  VV for the role played by strong annihilations (Wang, Liu, QZ)
Can we measure the isospin-breaking strong decays of charmonia? (Question from Yu-Qi Chen)

6. 7. Any suspicions on experimental data?
8. What is the desired precision?
9. Are there better ways to categorize data rather than into (quasi-two-body) VP, VT, PP, AP, …?

7. The “12%” rule and the “0.02%” rule
’ VP/P suppressed
’ PP enhanced
’ VT suppressed
’ BB obey/enh.
Multi-body obey/sup
Seems no obvious rule to categorize the suppressed, the enhanced, and the normal decay modes of J/ and ’.
The models developed for interpreting specific mode may be hard to find solution for other (all) modes.
The ’’ decays into light hadrons may (not) be large --- more data and more sophisticated analysis are needed to extract the branching fractions from the observed cross sections. Why D-wave decay width so large?
Model to explain J/, ’ and ’’ decays naturally and simultaneously?
S-D mixing in ’ and ’’ [J. L. Rosner, PRD64, (2001)] DD-bar reannihilation in ’’ (J. L. Rosner, hep-ph/ )
Four-quark component in ’’ [M. Voloshin, PRD71, (2005)]
Survival cc-bar in ’ (P. Artoisenet et al., PLB628, 211 (2005))
Other model(s)?

8. 10. (2S)-(1D) mixings: ’’ decays add more information or just trouble?
e+e- partial widths of psi’ and psi’’
Lineshape measurement of psi’’ is sensitive to the presence of the psi’, which provides a stringent constraint on the psi’ coupling to DD-bar.
ee  DD
Y.-J. Zhang and QZ, PRD2010; H.B. Li and M. Yang, PRD2010.

9. Inclusive non-DD hadronic cross sections from BES

10. A possible way to determine the mixing between (2S) and (1D)
(3770)
(3686) D
Y.-J. Zhang and QZ, PRD2010

11. 11. Can bottomonia decays help?

12. An analogue of the “12% rule” :

13. 12. Non-exotic explanations of many observations in the charmonium spectrum?
13. What’s the role played by open charm thresholds?
14. How to make a direct measurement?
Explanation of Y(4260) as a open charm effects (X. Liu et al. )
Nature of X(3900) (1) (Zhang, QZ; Wang, Liu, QZ)

14. Evidence for the open charm effects?
X(3900) ?
(3770)
(4040)
(4160)
(4415)
e+e-  DD
What is X(3900)?
Not inlcuded in PDG2010.
Not in charmonium spectrum
… …
Pakhlova et al., PRD77, (2008).

15. Where to test?
X(3900) ?
Wang, Liu, QZ, [hep-ph]

16. Thanks for your attention!
15. How can experimentalists & theorists make joint effort in understanding the “ puzzle” and even more?
More theory studies … …
More Experimental measurements … …
Thanks for your attention!

17. 致谢：
CCAST
南开大学
高能所

18. Next meeting?
长白山？天山？喜马拉雅山？