1. The X(3872) – enfante terrible of meson spectroscopy Belle Hot Topic (A.Bondar)
discovered by Belle (140/fb) in:
BK p+p-J/y
y’p+p-J/y
X(3872)p+p-J/y
M(ppJ/y) – M(J/y)
S.K. Choi , S.L.Olsen et al PRL 91,

2. Its existence is well established seen in 4 experiments
CDF
9.4s
11.6s
X(3872) D0
BaBar
X(3872)

3. X(3872) mass in p+p-J/y channel only
<MX>= ± 0.19 MeV
Belle meas.
new CDF meas.
CDF PRL103,152001(2009)
MD0 + MD*0.
2010
± 0.29 MeV/c2
Dm(deuteron) = -2.2 MeV
Dm = ± 0.35 MeV

4. diquark-diquark prediction:
X(3872)p+p- J/y in Belle
recent results
arXiv: fb-1
diquark-diquark prediction:
DM=8±3 MeV
Maiani et al PRD71,

5. p+p- system in X(3872)p+p- J/y comes from rp+p-
Belle
CDF: PRL
rp+p- lineshape p+
M(p+p- )
M(p+p- ) r p- w
X3872
J/y
What about r-w interference?

6. X(3872)p+p- J/y in CDF MX = 3871.61 ± 0.16 ± 0.19 MeV recent results
PRL103,
~6000 events!
MX = ± 0.16 ± 0.19 MeV

7. JPC of the X(3872) CDF definition Belle definition qX qr c qlep
X(3872) rest frame
r rest frame qX qr
J. Rosner PRD 70, (2004) c
qlep

8. Angular distributions for BKX(3872)KrJ/y
Partial Wave basis:
775 MeV
X(3872)r J/y is right at threshold  neglect higher partial waves
3872 MeV
3097 MeV
1++:
L: S-Wave D-wave
S: ,2
2-+:
L: P-Wave F-wave
S: , ,2
Only 1 amplitude: BLS=B01
 1 free parameter:
2 amplitudes: BLS=B11 & B12
 3 free parameters
normalization
normalization
complex

9. CDF results All JPC values other than 1++ or 2-+are
1++ fits well with no adjustable parameters
2-+ looks like 1++ for , at least with current statistics
All JPC values other
than 1++ or 2-+are
ruled out with high
confidence
CDF: PRL
1++ no adj. params
2- + 2 adj. params
1- -
O++

10. Angular Analysis at B-factories?

11. cosqX
cosc
cosqlep
cosqr
MC JPC= 2-+
a=0.6ei0
MC JPC= 1++
cosqX
cosc
cosqlep
cosqr

12. X(3872)g J/y (y’) ?? BaBar 2009: X3872g/y’ > X3872gJ/y ?!!
PRL 102,
3.6s
3.5s
X3872gy’
X3872gJ/y
bkg subtracted
B(B+K+ X3872)xB(X3872gJ/y)=(2.8±0.8)x10-6
B(B+K+ X3872)xB(X3872gy‘)=(9.5±2.8)x10-6
B(B+K+ X3872)xB(X3872gy’)
B(B+K+ X3872)xB(X3872gJ/y)
= 3.4 ± 1.4
X3872g/y’ > X3872gJ/y ?!!

13. Belle (May 2010): B+  K+ g J/y
1st evidence for B+K+ cc2
calibration reaction
cc1gJ/y
3.6s
cc2gj/y
Bf(B+K+ cc1)=(49±3)x10-5
Bf(B+K+ cc2)=(1.11±0.37)x10-5
B(B+K+ cc2)
B(B+K+ cc1)
= ± 0.007
0 -+,1++,1 --
factorization
suppression
penalty
V. Bhardwaj QWG 2010

14. X(3872)g J/y (y’) ?? Belle 2010: disagreement X3872gy’ X3872gJ/y
no signals!!
4.9s
B(B+K+ X3872)xB(X3872gJ/y)=(1.8±0.5)x10-6
BaBar: (2.8±0.8)x10-6
B(B+K+ X3872)xB(X3872gy’)
B(B+K+ X3872)xB(X3872gJ/y)
B(B+K+ X3872)xB(X3872gy’)<3.4 x10-6
<2.1 (90%)
BaBar: (9.5±2.8)x10-6
BaBar = 3.4 ± 1.4
disagreement

15. Possible 1++ cc assignment: cc1_ ‘
Mcc2=3930 MeV
set by: ‘
Mass is too low?
3872 vs 3905 MeV
G(cc1  g y’) ~180 keV
G(cc1  g J/y) ~14 keV
G(cc1  g y’)/G(cc1  g J/y)>>1 ‘ ‘
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

16. B  K w J/y (275M BB) Belle 2005: M(p+p-p0 )= mw±22 MeV “Y(3940)”
B(X3872wJ/y)
B(X3872p+p-J/y)
=1.0 ± 0.5
“Y(3940)”
PRL 94,
X(3872)”w” J/y
not seen in DD*

17. 2010: Y(3940) by BaBar M(p+p-p0 )= mw+18 MeV -40 BaBar B+  K+ w J/y
PRD 82,
M(p+p-p0 )= mw+18 MeV
-40
B+  K+ w J/y
B0  K0 w J/y
(467M BB)
BaBar:
M= ± 2.0 MeV
G = ± 5 MeV
B(B+K+ Y3940)xB(Y3940wJ/y): ( ) x10-5

18. What about X and Y interference?
2010: X3872w J/y by BaBar
M(p+p-p0 )= mw+18 MeV
-40
B+  K+ w J/y
BaBar
PRD 82,
Nevts =26.7±7.6
B0  K0 w J/y
X(3872)”w” J/y ??
B(X3872wJ/y)
B(X3872p+p-J/y)
=0.8 ± 0.3
S-wave fit prob: 7.1%  1++
P-wave fit prob: 61.9%  2-+
2-+ favored
What about X and Y interference?

19. Possible 2-+ cc assignment: hc2_
Possible 2-+ cc assignment: hc2
My”=3770 MeV
set by:
Mass is too high?:
3872 vs 3837 MeV
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:
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. Kalasnikova et al arXiv:
hc2ghc s& pphc modes expected to dominate

21. Summary Belle results contradict the BaBar claim of a
strong X3872gy’ decay width
Angular analyses of X3872p+p-J/y eliminate all
JPC other than 1++ & 2 -+
BK X3872 not distinguish (?) 1++ and 2-+
X3872”w”J/y line shape favors 2-+
(but only by ~1.5s)
The X3872 properties are not compatible with
conventional cc state in any case _

22. Thank You

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