1 Experimental review on “  puzzle” Changzheng YUAN Institute of High Energy Physics, Beijing 温都水城 2011 年 3 月 18 日

2 Contents experiments “12% rule” & “  puzzle” –A bit history –  & VP –VT –Other modes Questions for discussion

3 BES and CLEOc data Data BESIICLEOcBESIII (2012) J/  58 M--225 M (x5) ’’ 14 M26 M106 M (x5)  ’’ 33 pb pb pb -1 (2900 pb -1 ) Continuum 6.4 pb -1 (  s=3.65 GeV) 21 pb -1 (  s=3.67 GeV) 42 pb -1 (  s=3.65 GeV) PerformanceBESIICLEOcBESIII  p/p1.7%/  1+p 2  E/E22% /  PartIDdE/dx+TOFdE/dx+RICHdE/dx+TOF Coverage80%93% Almost no publications from BESIII yet …

4 The “12% rule” M. Appelquist and H. D. Politzer, PRL34, 43 (1975) This is the famous (or notorious) “12% rule”. It’s 13% now, was 12%, 14%, or 15%.

5  Violation found by Mark-II, confirmed by BESI at higher sensitivity.  Extensively studied by BESII/CLEOc  VP mode:  , K *+ K - +c.c., K *0 K 0 +c.c.,  0,…  PP mode: K S K L, K + K -,  +  -  [Xiaohu’s talk]  BB mode: pp, , …  VT mode: K*K* 2,  f 2 ’,  a 2,  f 2  3-body: pp  0, pp ,  +  -  0, …  Multi-body: K S K S hh,  +  -  0 K + K -, 3(  +  - ), … “12% rule” and “  puzzle” K*K  MARK-II

6 BESI studies of the “12% rule”

7 BESII: 强烈压低与反常增强 KSKLKSKL   多数过程满足 “ 12% 规则 ” 2. 首次观测到  (2S)   ，发 现强烈压低；比 “ 12% 规则 ” 压低近两个量级 3. 首次观测到  (2S)  VT ，发 现中等压低；比 “ 12% 规则 ” 压低几倍 4. 首次观测到  (2S)  K S K L ， 相对于理论预期反常增强 ! 理论预期

8  In Potential model, if J/ ,  ’, and  ’’ are pure 1S, 2S, and 1D states, one expects [PDG2010] Extension of the “12% rule” to  ’’  but  ’ and  ’’ are known not pure 2S and 1D states PRD17, 3090 (1978); 21, 203 (1980); 41, 155 (1990); …  Let’s look at data …

9 BESII CLEOc 229  0 s 196  0 s BES and CLEOc in good agreement! BESII: PLB619, 247 (2005) CLEOc: PRL94, (2005)  ’   +  -  0

10 Dalitz plots after applying  0 mass cut! Very different from J/  3  ! Similar Dalitz plots, different data handling techniques: PWA vs. counting! J/   ’   +  -  0 CLEOc BESII  ’   is observed, it is not completely missing, BR is at level!

11 J/   +  -  0 Make  mass cut, and count events PWA analysis assuming  interferes with excited  states L. P. Chen and W. Dunwoodie, Hadron’91, MRK3 data Very different! PDG: 1.69  0.15% 数据引用不对！

12 BESII 3.773GeV BES and CLEOc are in good agreement! X-section at  ’’ peak is smaller than at continuum! BESII: PRD72, (2005) CLEO: PRD73, (2006)  ’’   +  -  GeV 3.773GeV 3.670GeV CLEOc

13 BESII: PRD72, (2005) CLEO: PRD73, (2006) BESII BES and CLEOc are in good agreement! X-section at  ’’ peak is smaller than at continuum!  non-zero  ’’   amplitude.  ’’   +  -  CLEOc Subtle difference in handling efficiency and ISR correction.

14  ’’    Wang, Yuan and Mo:PLB574,41(2003) Total cross section  B depends on efficiency and ISR correction, efficiency and ISR correction depends on  B (s) ! Iteration is necessary! Three unknowns with two equations --- One can plot the BR versus phase .

15  ’’    BES data restrict BR and phase in a wide range C.L.): CLEOc data further restrict BR and phase in a ring*. At  =-90  : *Toy MC is used to get BR from CLEOc data (not CLEO official results)! BESII: PRD72, (2005) CLEOc: PRD73, (2006)

16 In S-D mixing model, using mixing angle θ=12°, using Rosner’s assumption (12% rule for 1S and 2S), one predicts Q ’ ρπ =( )% ! J/ ,  ’,  ’’   Partial width of ψ’’  ρπ is larger than that of ψ’  ρπ! hard to understand if ψ’’ is pure 1D state, also hard if ψ’’ is 2S and 1D mixture.  -90  or imperfect model?

17  ’  VP K * (892)K+c.c. K *0 Br ± =(2.9±1.7 ±0.4)  10 –5 Br 0 =(13.3±2.7 ±1.7)  10 –5 K*  Good agreement! Large Isospin violation! Both modes suppressed! BESII : PLB614, 37 (2005) CLEOc: PRL94, (2005) Br 0 =(9.2±2.7 ±0.9)  10 –5 Br ± =(1.3±1.0 ±0.3)  10 –5 BESII

BESII : PLB614, 37 (2005); PRD73, (2006) CLEOc: PRL94, (2005) J/ ,  ’  VP mode BESII: B(  ’)(×10 -5 ) CLEOc: B(  ’)(×10 -5 ) PDG2010 or my est.… B(J/  )(×10 -4 ) B(  ’)/B(J/  ) (%)  5.1±0.7± ±0.2242±280.13±0.05  (2150)  19.4± N/A +-0+-0 18.1±1.8± ±2.8207±120.92±0.11 K* 0 K 0 +c.c. 13.3±2.7± ± ±3.12.6±0.6 K* + K - +c.c. 2.9±1.7± ± ± ±0.20  ± ±0.24.5±0.53.7±1.2  ± ± ± ±3.4  ’ ±0.33N/A1.05±0.1818±16  <0.40N/A<0.064N/A  3.3±1.1± ±0.47.5±0.83.0±1.2  ’ 3.1±1.4±0.7N/A4.0±0.77.8±4.1  <3.1< ±2.0<0.53  ’ ±0.7N/A1.82±0.2114±11

19 Search for  ’’  VP CLEO: PRD73, (2006) Same operation as for  ’’   should done for all the modes to extract the BRs of  ’’ decays. BR(  ’’  final state)   =-90 degrees as in J/  and  ’ decays?  Any way to choose one solution? Some x-sections agree, some very different.

20 f 2 (1270) B.G.(M.C.) B.G.(  )  ’  V T B.G. a 2 (1320) BESII ： PRD69, (2004)

21 B.G. K * 2 (1430) K * (892)  ’  V T B.G. f 2 ' (1525) f 0 (980) BESII ： PRD69, (2004)

22 † This value from DM2 only Suppressed!! 12 % rule ( pQCD rule )  ’  V T VT mode B  ’  X (10 – 4 ) (BES-II) B J/  X (10 – 3 ) (PDG2010) Q h (%)  f ± 0.41 ± ±0.64.8±1.5  a ± 0.73± ±2.22.3±1.1 K * K * ± 0.32 ± ±0.63.1±1.3  f 2 ' 0.44 ± 0.12 ± ±0.21 † 3.6±1.5 BESII ： PRD69, (2004)

23 Multi-body  ’ decays BESII: PRD71, (2005) Some modes are suppressed, some are enhanced, while some others obey the 12% rule! CLEOc: PRD72, (2005) BESII, PRD73, (2006) CLEOc: PRL95, (2005)

24 Multi-body  ” decays 25 modes, no significant signal observed over continuum expectation. CLEOc: PRL96, (2006)

25 Multi-body  ” decays [references by PDG2010] Many publications, but no significant signal in even one single mode! (mystery!!)

26 BESIII PRL105, (2010) NEW information! J/  &  ’   0,  &  ’ 4.6  4.3         )  ’   ’  ’   0  ’   ModeB(  ’) [x10 -6 ]B(J/  ) [x10 -4 ]Q (%)     1.3  1.38    0.04  ’126    0.2

27 The “12%” rule and the “0.02%” rule   ’  VP/  P suppressed   ’  PP enhanced   ’  VT suppressed   ’  BB obey/enh.  Multi-body obey/sup 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)] [  Wang Ping] 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)? 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 hard to find solution for other (all) modes.

28 Summary Lots of progress from BESII and CLEOc in vector charmonia decays. Hadronic decays of J/ ,  ’, and  ’’ are studied extensively and simultaneously to understand the decay dynamics. “  puzzle” remains a puzzle,  ’’ charmless decays is observed in inclusive mode, but the total rate for the charmless decay is very uncertain & suspecious. More studies are needed (and expected) at BESIII! Thanks a lot!

29 你再问我为什么， 我就揍你！ 为什么？

30 For discussion Do you have any suspicions on experimental data? [Still assumptions in extracting experimental results, be careful in citing BRs] What is the desired precision? Are there better ways to categorize data rather than into (quasi-two-body) VP, VT, PP, AP, …? Are there crucial modes still missing? How reliable is the 12% rule? J/  enhanced?  ’ suppressed? Or both? Should there be difference between strong decays and EM decays (in terms of the BR ratio)?

31 For discussion  ’’ decays add more information or just trouble? Can bottomonia decays help? How can experimentalists & theorists make joint effort in understanding the problem?

32 CLEO preliminary results never published!

33