1. for the BES Collaboration
c cJ Decays at BESII
Rong-Gang Ping
IHEP, Beijing
for the BES Collaboration
高能物理学会第七届全国会员代表大会暨学术年会
2006年10月28－11月1日 ,广西.桂林
高能物理学会第七届全国会员代表大会暨学术年会, /28-11/01

3. P-wave charmonia decays
Data samples
14M
2001.Nov.01to 2002.Mar.02 4M 3M
P-wave charmonia decays
c0 , c1 , c2
6.42 pb-1 continuum data at
Ecm=3.65 GeV for bkg study.

4. Motivation :
▲Compared with vector and pseudoscalar mesons, little information on scalar and tensor mesons are known.
▲ The decays of ccJ provide a direct window on studing of 0++ and 2++ mesons.
Different way for scalar study:
Start from JPC=0++, 1++, 2++
Start from gluon+gluon
Pair production of scalars, very different from J/ decays

5. Event level 5C-fit c0 c0      K  K  1371 events 1. Qi = 0 ;
BES: PRD72, (2005)
c0(3414.7±0.6MeV)
1. Qi = 0 ;
2. p()+p(  ) > 650 MeV
[BG:’   J/ ];
3. Prob(    K K )> Prob(      )&
Prob(    K K )> Prob(  K K K K );
4. M( )  [497±50] MeV/c2 & second vertex <5mm [BG: KS ];
c1(3511.3±1.3MeV)
c2(3556.4±0.9MeV)
Event level
5C-fit
1371 events
1.Avoid introducing a huge number of partial waves;
2. constrained by present statistics; our study is devoted to c0      K  K 
c0

6. (    )( K  K ) BES: PRD72, 092002 (2005) f0(980) f0(2200)
(770)
Q. Zhao, PRD72, (2005), try to understand these data and the scalars …

7. (K    )(K    ) BES: PRD72, 092002 (2005) K*(892)0 With Without
Kappa-kappa
Without
Kappa-kappa
S=39.
K*0/2(1430)
K*0(1950)

8. (K   )K 1371 events BES, c0→+K+K BES: PRD72, 092002 (2005)
M(K ) [896±60] MeV
K1(1270)
The mixing angle between K1A and K1B >57 degrees, while in ’ decays to K1K, the angle is <29 degrees (PEL83p1918). Why?
M( ) [700,850] MeV

9. From the c0      K  K  decay fit results, it is found that
scalar resonances have larger decay fractions compared to those
of tensors, and such decays provide a relatively clean laboratory
to study the properties of scalars, such as f0(980),f0(1370),f0(1710),
f0(2200) and so on.

12. Pair production of vectors
cJ 
c0
c1
c2
Improved precision over PDG (BESI) results on cJKKKK and .
First measurement of cJKK.

13. Pair production of vectors38
c0 28
c2
First observation:
B(c0) = (2.290.580.41)10-3
B(c2) = (1.770.470.36)10-3
BES: PLB630, 7 (2005)

14. hep-ex/
 cJ→PPP
c2
c1
Event selection:

15. h Nsig=418± 60 Nsig=222±28 (8.8s) Nsig=58± 14 (4.5s) h sideband
a0 sideband

16. by spin-parity selection;
c0→PPP is suppressed
by spin-parity selection;
cJ→KK and 

17. Phys.Rev. D74 (2006)
cc0 cc1 cc2

18. Phys.Rev. D74 (2006)

20. cJ  c0  Evidences for c0 and c0,2.
BES: PRD73, (2006)
cJ 
c0 
Evidences for c0 and c0,2.
Agree with COM and QCM predictions.

21. Summary of the test of color octet mechanism
● For χcJ →PP, the theoretical results are in general good agreement with experimental values .
●For χc0 →B Bbar, there is no reliable theoretical interpretation. The experimental values of Br(χcJ →Λ Λbar) decays are quite larger than theo. values.
● More experimental information are desirable for determining the color octec wavefunction of χcJ states.

22. Summary
Thanks a lot !

23. Thank you

24. Mixing of the K1(1270)-K1(1400)
Two lowest-lying Axial-Vector meson octets:
Spin singlet (1P1) Spin triplet (3P1)
KB (b1) KA (a1)
K1(1270): K; K1(1400): K*
a1: fobidden by G parity, SU(3) symmetry
KAKbar disallowed, pure KBKbar
meanwhile, 450
 roughly equal of K1(1270)-K1(1400)
Here >570 is requirement.