1. Charmonium experimental overview
Stephen Lars Olsen
Seoul National University
Topical Seminar on Frontier of Particle Physics
Hu Yu Village, Beijing CHINA
August 27-28, 2010

2. outline
Lecture1: History & the discovery of the bound charmonium states
Lecture 2: The non-charmonium, charmonium-like states & the future
Yesterday
Today

3. Summary (lecture 1)
The charmonium spectrum is strong evidence that hadrons are
composed of spin=1/2 constituent particles
All of the charmonium states below the M=2mD “open charm”
threshold have been found
Most of the above-threshold 1- - states & the cc2’ have been
identified
The masses of the assigned states match theory predictions
-variations are less than ~50 MeV
Transitions between charmonium states are in reasonably good
agreement with theoretical expectations

4. y(4415)
y(4150)
y(4040) c’ c2 y”
2mD0

5. g Transitions M1 transitions (G(keV)) g e- E1 transitions
J/y g hc ± 0.4
y’ g hc ± 0.2
Th Expt
pp,h,p0 g e-
E1 transitions
Th Expt
± 4
± 3
± 3
± 51
± 48

6. Hadronic transitions y’p0J/y y’ppJ/y Ispin violation: ~1/200
y’  J/y +hadrons
Gexp(keV)
y‘p+p- J/y ± 7
y’ h J/y ± 1
y’ p0J/y ±0.1
pp, h, p0
pp,h,p0 g y’
J/y
Ispin violation:
y’p0J/y
y’ppJ/y
~1/200

7. Predictions for the y” Gexp(keV) g g g e- y”p+p- J/y ~80 55 ± 15
th Expt
y”p+p- J/y ~ ± 15
y” g cc ± 17
y” gcc ±30 g g
pp,h,p0 g e-

8. Can we find other above-threshold states?
y(4415)
These 2 may
be simpler
y(4150)
y(4040) c’ c2
hc2
yc2 y”
2mD0

9. yc2 (hc2)DD violates parity_
2-+ &  DD not allowed
hc2
yc2
Spin=0 c D
J = 2
P=-1
D0 or D+ q
yc2 c
(or hc2)
J = L
P = (-1)L
For J = 2
P = (-1)2 = +1 q c q D c
D0 or D-
Spin=0
yc2 (hc2)DD violates parity

10. Lowest possibility is DD* (or D*D)_ _
Lowest possibility is DD* (or D*D)
Spin=0 c D
J = 2
P=-1
D0 or D+ q c
yc2
J = L + S
P = (-1)L
For J = 2, L=1 is OK
P = (-1)1 = -1 q
(or hc2) c q D* c
D*0 or D*-
Spin=1
yc2 (hc2)DD* doesn’t violate parity

11. yc2 & hc2 are expected to be below mD+mD* threshold

12. Belle: search for yc2 in BKyc2K(p+p-J/y)
Eichten et al:
PRL 98, (2002) c _
yc2 p+p- J/y??
B meson
y’p+p-J/y s q _ K
yc2???
M(p+p- J/y)-M(J/y)
Belle PRL 91, (2003)

13. X(3872)
MX=3872.0±0.6 MeV
G<2.3 MeV
Belle PRL 91, (2003)

14. X3872 is well established seen in 4 experiments
CDF
9.4s
11.6s
X(3872) D0
BaBar
X(3872)

15. “Look for Xg cc1, you should
Is the X(3872) the yc2?
Bf(yc2g cc1)
Bf(yc2p+p-J/y)
Eichten et al:
PRL 98, (2002)
>5
“Look for Xg cc1, you should
be flooded by events”
Eichten

16. Belle search for X(3872)gcc1
Belle PRL 91, (2003)
3872
Bf(yc2g cc1)
Bf(yc2p+p-J/y)
<0.9
The X(3872) is not the yc2!!

17. If not yc2, what??? Agreement  Contradiction 
Look for other decay modes:
X(3872) g J/y ?
X(3872) g y’?
BaBar 2009:
BaBar 2009:
Yes
Yes
Agreement 
Contradiction 
PRL 102,
Belle 2010:
Belle 2010:
Yes No
V. Bhardwaj QWG 2010

18. C(X3872) = + C(X3872) must be (-)(-) = + X3872 g J/y
if C(X3872) is + :
p+p- system in X3872p+p- J/y must come from rp+p- p+
C = - r
Belle agrees
CDF agrees p-
X3872
rp+p- lineshape
J/y
C = -
M(p+p- )
M(p+p- )

19. JPC of X3872 0-+ ?? p+ r p- p* X3872 J/y mutually perpendicular m+ p+
0-+ ??
spin polarization
vectors p+ r p- p*
X3872
J/y
mutually perpendicular m+ p+ m- p-

20. Does the X(3872) JPC = 0-+ ??
0-+
!!!
No, the X(3872) cannot be 0-+

21. Does the X(3872) JPC = 1++ ?? B mutually perpendicular X(3872) K S=0
Sx=0

22. 1++ fits well
Belle Data

23. CDF angular correlation analysis
Only 1++ or 2-+ fit data
PRL
1++ no adj. params
2- + 2 adj. 2arams
1- -
O++
1++ fits well with no adjustable parameters
2-+ looks like 1++ for , at least with current statistics

24. a 1++ cc state for the X3872? _ c’ c.f.: G(y’p0J/y)≈0.4 keV ‘
set by:
Mcc2=3930 MeV ‘
Mass is too low?
3872 vs 3905 MeV
G(cc1  g y’) ~180 keV
G(cc1  g J/y) ~14 keV
G(g y’)/G( g J/y)>>1 ‘ c’ ‘ c1
T.Barnes et al PRD 72,
Gp+p- J/y =(3.4±1.2) GgJ/y~45 keV
huge for Isospin-violating decay
c.f.: G(y’p0J/y)≈0.4 keV

25. a 2-+ cc state for the X3872? _ hc2 BKhc2 violates factorization
set by:
My”=3770 MeV
Mass is too high?
3872 vs 3837 MeV
T.J. Burns et al arXiv:
G(hc2  g y’) ~0.4 keV
G(hc2  g J/y) ~9 keV
G(hc2 g y’)/G(hc2 g J/y)<<1
Y. Jia et al arXiv:
hc2
Gp+p- J/y =(3.4±1.2) GgJ/y ~30 keV
huge for Ispin-violating decay
c.f.: G(y’p0J/y)≈0.4 keV
BKhc2 violates factorization
BKhc not seen
BKcc2 barely seen
hc2  DD* expected to be tiny
Belle & BaBar:
G(XDD*)/G(XppJ/y)=9.5±3.1
Y. Kalasnakova et al arXiv:

26. If not charmonium, what is it?

27. CDF X(3872)p+p- J/y Mass MX = 3871.61 ± 0.16 ± 0.19 MeV
recent results
~6000 events!
arXiv:
MX = ± 0.16 ± 0.19 MeV

28. M X(3872) ≈ MD0 +MD*0 <MX>= 3871.46 ± 0.19 MeV
new Belle meas.
new CDF meas.
MD0 + MD*0
3871.8±0.4 MeV
dm = ± 0.41 MeV

29. X(3872) looks like a D0D*0 “molecule”
N. Tornqvist
Z. Phys C 61, 525 (1994)
predicted by Tornqvist in 1994, requires: JPC = 1++ or 0-+

30. States near 3940 MeV

31. Search for other states in BK p+p-p0 J/y decays_
J/y
B meson
wp+p-p0 s q _ K

32. M(w J/y) Y(3940) Y3940 p+p-p0J/y?? w M=3940 ± 11 MeV G= 92 ± 24 MeV
unexpected peak at 3940 MeV
Y3940 p+p-p0J/y??
Y(3940) w
M=3940 ± 11 MeV
G= 92 ± 24 MeV
S.-K. Choi et al (Belle)
PRL94, (2005)

33. Y(3940) confirmed by BaBar B±K±wJ/y B0KSwJ/y ratio M(wJ/y)
PRL 101,
Some discrepancy in M & G; general features agree

34. Belle-BaBar direct comparison
Same binning
(Belle published
result : 253 fb-1)
492fb-1
Belle will update with the complete (4S) date set later this Fall

35. _
Does Y(3940)  DD* ? _
BKDD*
3940 MeV
3940 MeV
No signal:

36. Study e+e-  J/y + anything
detected
J/y e+ e-
J/y recoil system
is undetected
Recoil Mass:

37. s(e+e- J/y+cc) unexpectedly big_
Unexpected peak at 3940 MeV
e+e- J/y+hc

38. Use “partial reconstruction” to study X3940 DD or DD*_ _
J/y e+ e-
reconstruct
these _
“Recoil” D(*)
undetected
(inferred from
kinematics) _ _ _
D (or D*)
D (or D*)

39. X(3940) DD* is large _ _ _ M = 3942 +7 ± 6 MeV -6
Gtot = ±12 MeV
Nsig = ± 11evts -6
-15 _ _
-16
e+e-  J/y + DD*
arXiv:
PRL 98, (2007)
Bg subtracted

40. Use “partial reconstruction” to search for X(3940)wJ/y
“Recoil” J/y
undetected
(inferred from
kinematics)
reconstruct
these p
J/y p p
w3p
3940 MeV
no signal:

41. X3940 & Y3940 are not the same from: from: e+e- J/y DD* & J/y wJ/y_
from:
B K wJ/y & KDD* _

42. M(D*D*) has a peak too _ _ _ It has to have C=+; most likely 0-+
e+e-  J/y D* D*
M = ± 15 MeV
Gtot = ± 21MeV
Nsig = ± 11evts
-20
-61 -8
arXiv: _
It has to have C=+; most likely 0-+

43. cc assignments for X(3940), Y(3915) & X(4160)?_
hc’’’
4160MeV
hc”
cc0’
3940MeV
3915MeV
Y(3915) = cco’? G(wJ/y) too large?
X(3940) = hc”?  mass too low?
X(4160) = hc”?  mass too high?
X(4160) = hc”’?  mass much too low?

44. 1- - states seen via “radiative return”
“initial-state-radiation” photon: gISR kg
1- - E’
Ecm
if kg = 3.8~4.5 GeV, E’ = 3~5GeV

45. Radiative return Ecm(GeV) B-factory energies g ss cc bb 3~5 GeV

46. e+e-  gisr Y(4260) at BaBar p+p- J/y BaBar PRL95, 142001 (2005)
fitted values:
233 fb-1
M=4259  8 +2 MeV
G = 88  MeV -6 -9
Y(4260)
~50pb

47. “(4260) confirmed by Belle BaBar values: M=4247  12 +17 MeV -32
G = 108  19 ±10 MeV
-32
M=4259  8 +2 MeV
G = 88  MeV -6 -9
M=4008  MeV
G = 226  44 ±87 MeV
-28
???
C.Z Yuan et al (Belle)
PRL 99,

48. Not seen in e+e-  hadrons
J.Z.Bai et al (BES), PRL 88, (2006)
s(e+e- hadrons)
s(e+e-  m+m-)
No sign of Y(4260)D(*)D(*)
4260
speak(Y(4260)+p-J/)~50 pb
~3nb
Huge by charmonium
standards
BES data
G(Y4260p+p- J/y) > 90% CL
X.H. Mo et al, PL B640, 182 (2006)

49. cc assignment for the Y(4260)??
only unfilled
1- - state left
33D1
4260MeV
Y(4260) = 33D1?  mass too low & G(p+p-J/y) too large

50. another peak in e+e-  gISRp+p- y’
BaBar
M=4324  24 MeV
G = 172  33 MeV
Peak is 4324 MeV, distinct from 4260 MeV

51. 4325 MeV p+p-y’ peak in Belle
Two peaks!
(both relatively narrow)
(& neither consistent with 4260)
M=4361  9 ±9 MeV
G = 74  15 ±10 MeV
M=4664  11 ±5 MeV
G = 48  15 ±3 MeV
4260
BaBar values
M=4324  24 MeV
G = 172  33 MeV
X.L. Wang et al (Belle)
PRL 99, (2007)
548 fb-1

52. At least three peaks for only one empty level
4664MeV
33D1
4361MeV
4260MeV

53. exclusive e+e- gISRD(*)D(*) channels

54. Sum of all exclusive contributionsDD
DD*
D*D*
DDπ
Sum of all exclusive contributions
DD*π
Λ+c Λc
Only small room for unaccounted contributions
Charm strange final states
Limited inclusive data above 4.5 GeV
Charm baryons final states
Phi to Psi 2009
Galina Pakhlova

55. Experiment for BES III?: Search for other Y(4260) modes
Scan the 4260 ± 100 MeV region & measure dominant channels to ± 1%
DD*
D*D*
s  2nb
20 points  ~1 year of BES III data taking

56. The Z(4430)+  p+y’ “smoking gun” for a four quark meson?B0 K- B0

57. BK±p y’ (in Belle) ??
M2(p+y’)
K*(1430)K+p-?
K*(890)K+p-
M2(K+p-)

58. The Z(4430)± p±y’ peak “K* Veto” Z(4430) BK p+y’ M2(p±y’) GeV2
M (Kp’) GeV
Z(4430)
M2(p±y’) GeV2
M(p±y’) GeV
M2(Kp’) GeV2
“K* Veto”

59. Shows up in all data subsamples

60. Could the Z+(4430) be due to a reflection from the Kp channel?

61. Cos qp vs M2(py’) p qp +1.0 M2(py’) cosqp -1.0K
+1.0
22 GeV2
(4.43)2GeV2
0.25
M2(py’)
cosqp
16 GeV2
-1.0
M (py’) & cosqp are tightly correlated;
a peak in cosqp  peak in M(py’)

62. S- P- & D-waves cannot make a peak (+ nothing else) at cosqp≈0.25
not without introducing other, even more dramatic
features at other cosqp (i.e., other Mpy’) values.

63. HW p qp y’ K
Compute the relation between cosqp and M2(py’)

64. But…

65. BaBar doesn’t see a significant Z(4430)+
“For the fit … equivalent to the Belle analysis…we obtain mass
& width values that are consistent with theirs,… but only ~1.9s
from zero; fixing mass and width increases this to only ~3.1s.”
Belle PRL: (4.1±1.0±1.4)x10-5

66. Reanalysis of Belle’s BKpy’ data using Dalitz Plot techniques

67. 2-body isobar model for Kpy’
Our default model
ky’
K*(890)y’
K*(1410)y’
K0*(1430)y’
K2*(1430)y’
K*(1680)y’
KZ+
K*y’ B
K2*y’
Kpy’
KZ+

68. Results with no KZ+ term2 1 1 2 3 4 5 C B A 3 4 A B 5 C
fit CL=0.1% 51

69. Results with a KZ+ term 2 1 B 1 2 3 4 5 A 3 4 C B C A 5
fit CL=36%

70. Compare with PRL results
K* veto applied
With Z(4430)
Signif: s
Published results
Without
Z(4430)
Mass & significance similar,
width & errors are larger
BaBar:
Belle: = ( )x10-5
No big contradiction

71. Variations of the model
Z(4430)+ significance
Others: Blatt f-f term 0r=1.6fm4fm; Z+ spin J=0J=1; incl K* in the bkg fcn

72. HW Devise strategies to determine JP of the Z(4430)+ p JP=0- JP=0-B K
Spin=0 y’
JP=1-
Are any JP values immediately ruled out?
Can we use parity conservation? For which decays?

73. The Z1(4050)+ & Z2(4250)+ p+cc1 peaks
R. Mizuk et al (Belle), PRD 78, (2008)

74. Dalitz analysis of B0K-p+cc1
DE GeV
??? G
K3*(1780)
K*(890)
K*(1680)
K*(1400)’s
M (J/yg) GeV

75. BKpcc1 Dalitz-plot analyses
Default Model
kcc1
K*(890)cc1
K*(1410)cc1
K0*(1430)cc1
K2*(1430)cc1
K*(1680)cc1
K3*(1780)cc1
KZ+
K*cc1 B
K2*cc1
Kpcc1
KZ+

76. Fit model: all low-lying K*’s (no Z+ state)b c d g f e a b e f c d g
C.L.=310-10

77. Fit model: all K*’s + one Z+ stateb c d g f e a b e f c d g
C.L.=0.1%

78. Are there two? ? ? ? ? a b c d

79. Fit model: all K*’s + two Z+ statesb c d g f e a b e f c d g
C.L.=42%

80. Two Z-states give best fit
Projection with K* veto

81. Systematics of B0 → K- π+ c1 fit
M=1.04 GeV; G=0.26 GeV
Significance of Z1(4050)+ and Z2(4250)+ is high.
Fit assumes JZ1=0, JZ2=0; no signif. improvement for JZ1=1 &/or JZ2=1.

82. Z states cannot be charmoniumd
Need confirmation from other experiments (CDF? … D0?)

83. Are there XYZ counterparts in the b- and s-quark sectors?
What about here?
233 fb-1
Y(4260)

84. b-quark threshold region

85. Belle: G((4S)p+p-(1S))
477 fb-1 2S 3S 4S
(4S)  (1S) p+p-
52±10 evts
N(4S)
N(p+p-1S)
B(Y4Spp1S)
G(Y4Spp1S)
Gtheory
535x106
52±10
9 ± 2 x10-5
1.75 ± 0.35 keV
1.47±0.03 keV

86. Belle: G(5Sp+p-1S) 1/20th the data & 1/10th the cross-section
23.6 fb-1
325±20 evts!
1/20th the data &
1/10th the cross-section
>6 times as many events!!
K.F. Chen et al (Belle)
PRL 100, (2008)

87. Assuming the source is the (5S)
Partial Widths
Assuming the source is the (5S)
PDG value taken for (nS) properties
N.B. Resonance cross section ± nb at GeV
PRD 98, (2007) [Belle]
>300 times bigger than that for the 4S!!
c.f.
(2S)  (1S) p+p- ~ 6 keV
(3S) keV
(4S) keV

88. Are these events from the 5S?
s(e+e-  p+p-nS ) from a cm energy scan
Fitted parameters
5S peak position
PDG(5S):
K.F. Chen et al (Belle)
arXiv:

89. Peak & width in p+p-(nS) different from (5S) &(6S)
e+e-p+p-Y(nS)
Simplest interpretation:
b-quark-sector equivalent to
the c-quark-sector’s Y(4260)
e+e-  hadrons

90. Y(4260) equivalent with s-quarks?
e+e-  g f0(980)f
Y(2175)f0(980)f
s(e+e-  p+p- f(1020))
BaBar
f0(980)p+p-
M(f0(980)f)
BaBar, PRD 74,

91. Confirmed by BES & Belle
confirmed by BESII
in J/y  h f f0(980)
s(e+e-  f0(980)f(1020))
BES
Belle
M(f0(980)f GeV
C.P.Shen et al (Belle) arXiv:
M.Ablikim et al (BES)
PRL 100, (2008)

92. The “XYZ” mesons

93. Concluding remarks Charmonium mesons are strong evidence for quarks
All the lowest-lying charmonium states have been found
Good agreement between their measured properties & theory
Charmonium is the “best understood” hadronic system
Higher-mass charmonium meson searches have produced surprizes
A number of non-charmonium meson candidates have been found.
They have strong transitions to ordinary charmonium states
Corresponding states sem to exist in the b-qyark & s-quark sectors
Most of the new states are in the BEPC-II Ecm range
We have to figure out how to access them (& find new ones)
So far only final states with a J/y or y’ have been studied
e.g., final states with an hc or a hc may be interesting
Lots of opportunities for BES III
Need creativity and new ideas

94. Thank You 謝謝
감사합니다