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

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.

Branching ratios for J/ (cc)  V P

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? ……

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)

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, …?

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, 094002 (2001)] DD-bar reannihilation in ’’ (J. L. Rosner, hep-ph/0405196) Four-quark component in ’’ [M. Voloshin, PRD71, 114003 (2005)] Survival cc-bar in ’ (P. Artoisenet et al., PLB628, 211 (2005)) Other model(s)?

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.

Inclusive non-DD hadronic cross sections from BES

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

11. Can bottomonia decays help?

An analogue of the “12% rule” :

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)

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, 011103(2008).

Where to test? X(3900) ? Wang, Liu, QZ, 1103.1095[hep-ph]

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!

致谢： CCAST 南开大学 高能所

Next meeting? 长白山？天山？喜马拉雅山？