X(3872), Y(3915) & Charged Zc states
Stephen Lars Olsen
Seoul National University
New Hadron Spectroscopies/Dynamics WS
Haeundae, Busan Nov. 19, 2012
charmonium (cc) meson spectra
_
Charmonium
All of the states below 2mD
have been assigned
Many radiative transitions have
been measured with widths
that agree with theory
A number of hadronic transitions
(y’ppJ/y; hJ/y; p0J/y; p0hc)
have been measured, also with
widths that agree with theory
Above 2mD a number of states
have been found that have defied
assignment to a charmonium level
& most have anomalously large
hadronic transition widths
e.g.; G(y’hJ/y  keV; G(y3ShJ/y) ≈ 1MeV
G(y’p+p-J/ykeV; G(Y4260)p+p-J/y) > 1MeV
bottomonium
p+pG(MeV)
p+pp+p
-
p+p-
p+p-
p+p-
x102
The X(3872)
Latest result on the X(3872)
CMS at HCP2012 (Kyoto) last week
X(3872) production very similar to y’ production  X(3827) has a significant cc component
_
M(p+p-) for X(3872)p+p-J/y
rp+pp+p- S-wave
p+
r
X387
2
E.A. Yetkin, parallel talk Hadron Collider Physics Symposium (Kyoto Nov. 2012)
J/y
p-
What else we know about the X(3872)
•M(X3872) – (mD0 + MD*0 ) = (-120 ± 350) keV
•G(X3872) < 1.2 MeV
•JPC = 1++ likely, JPC= 2-+ still possible
•Bf(BKX3872) x Bf(X3872p+p- J/y) = (8.6 ± 0.8) x 10-6
•Bf(X3872p+p- J/y) > 2.6%
•Bf(X3872D0D*0)/ Bf(X3872p+p- J/y) =9.3±2.7
_
•Bf(X3872 g J/y) /Bf(X3872p+p- J/y) = 0.21±0.08
•Bf(X3872 wJ/y) /Bf(X3872p+p- J/y) = 0.8±0.03
•No Isospin partners are found  I=0
•this means X3872p+p- J/y violates Ispin symm.

_
++
1 cc
assignment?
‘
cc1
•Mass is too low?
•3872 vs 3905 MeV
nr=2 splitting> nr=1
•Theory: G(cc1  gy) 10
G( cc1  gJ /y )
expt upper limit: <2.1
T.Barnes et al PRD 72, 054026

•Expt:
G(cc1  r 0 J /y )
 3.4 1.2
G(cc1 gJ /y )
use theory: G(cc1 gJ /y) 14keV
 G(cc1  r 0 J /y )  45keV

c.f.: G(y’p0J/y)≈0.4 keV

3872 MeV
_
-+
2 cc
assignment? hc2?
•Mass is too high?:
•3872 vs 3837 MeV
•Expt:
G(hc2  r 0 J /y )
 3.4 1.2
Ghc2  gJ /y )
use theory:
G(hc2 gJ /y)  9keV
Y. Jiaet al arXiv:0107.4541

 G(hc2  r 0 J /y )  30keV
c.f.: G(y’p0J/y)≈0.4 keV
•Theor: BKhc2 violates factorization
•BKhc not seen
•BKcc2 barely seen
_
•Theory: hc2  DD* expected to be tiny
Y. Kalasnikovaet al arXiv:1008.2895
•Belle &_BaBar::
G(XDD*/G(Xp+p-J/y9.5±3.
hc2ghc(1S) & pphc modes expected to dominate
If not cc, then what?
_
Possibilities that have been suggested:
tightly bound
diquark-diantiquark
loosely bound
meson-antimeson
“molecule”
_
c q_
q c
In color space:
_
c
red+blue=magenta
(antigreen)
A colored diquark
is like a antiquark
cyan+yellow=green
(antimagenta)
A colored diantiquark
is like a quark
This requires existence of isospin (& octet)
partner states, which are not seen.
s
_ p,s
_ c
s
This likes M(X3872) ≈ mD0+mD*0
& can explain large Ispin violation
X(3872)-J/y relative sizes
drms(208Pb nucleus)≈5.5 fm
+
+
208Pb +
+ + ++
+++
+
+
+
+ + +
++ +
X(3872)
drms(X3872) ~ 8 fm
drms(J/y) ≈ 0.4 fm
J/y
Volume(J/y) /Volume(X3872) ≈ 10-4
•How can such a fragile object be produced in H.E. pp collisions? heavy ion collisions??
C. Bignamini--etarXiv
al, PRL 0906.0882:
103, 162001:
sCDF(meas)>3.1±0.7nb
vs
stheory(molecule)<0.11nb
Is the X(3872) the cc1
‘ ?
M
cc potential
3905 mass value
_
≈8 MeV off mass shell
MX(3872) –(MD0 + MD*0) = -0.12 ± 0.35 MeV
_
MX(3872) –(MD+ + MD*-)= -7.74 ± 0.35 MeV
_
Best guess: X3872 is a cc1
‘ - DD*-molecule
mixture, brought down in mass to mD0+mD*0
by some mechanism I don’t understand.
3872
MD0 +MD*0
What pulls M down from 3905 MeV
--past the D+D*- threshold—
exactly to the D0D*0 threshold?
_
≈on mass shell
DD* screening
3880
MD+ +MD*-
X
Isospin Violation in X(3872) decay:
c.f. B.-Q. Li & K.-T. Chao PRD 79, 094004
The Y(3915)
aka X(3915)
Y(3915)wJ/y
K
B
Belle
2005
Y
B+K+
w
w
Y
Belle
wJ/y
2010
M=3943 ± 17 MeV
G= 87 ± 34 MeV
2008
gg  wJ/y
M=3915 ± 5 MeV
G= 17 ± 11 MeV
M(wJ/y)
M(wJ/y)
BaBar
J/y
J/y
gg  wJ/y
B+K+ wJ/y
M=3919± 3 MeV
G= 13 ± 7 MeV
B0K0 wJ/y
M=3915 ± 5 MeV
G= 34 ± 13 MeV
M(wJ/y)
M(wJ/y)
BaBar
2012
BaBar measurements favor JPC=0++
ql*
n
ql*
qln
0+
2+
BaBar PRD 86, 072002
arXiv:1207.2651
(2012)
What we know about the Y(3915)
•M(Y3915) = 3917 ± 3 MeV
•G(Y3915) = 21 ± 7 MeV
•Bf(BKY3915) x Bf(Y3915wJ/y) = (5.1 ± 1.0) x 10-5
Published data
•G(Y3915gg) x Bf(Y3915wJ/y) = 54 ± 9 eV
•Bf(Y3915D0D*0) /Bf(Y3915wJ/y) < 1.3
_
•JPC = 0++ likely
•Bf(Y3915DD) /Bf(Y3915wJ/y) < 1.3
_
•G(Y3915wJ/y) ≈1MeV
My estimates
(see backup slides)
Y(3915) = cc‘0 charmonium state?
_
If Y(3915) = cc0
‘:
23P0 cc state
-G(cc0wJ/yc0) ≈ 1 MeV
too wide for hadronic
charmonium transitions
c.f.: G(y’p+p-J/y)≈0.1 MeV
- mass is to high:
M(c‘c2)-M(c‘c0) ≈ 14 MeV
≈1/10th the n=1 splitting:
M(cc2)-M(cc0)=141 MeV
- Y(3915)DD not seen?
theory predicts:
G(c‘c0DD) ≈ 30 MeV
my estimate:
G(Y(3915)DD) < 2 MeV
M=3929 ± 5 MeV
_
_
_
Y(3915) & thresholds
3.95
D+s D-s
Y(3915)
M (GeV) 3.90
D+D*D0D*0
3.85
arXiv:1101.2071
Only VV couplings (no DD coupling):
Gtot= 17MeV
+
charged Z charmonium-like states
c
u c
d c
Smoking guns for 4-quark states
&
BK p+ y’
BKp+ cc1
M2(p+cc1)
M2(p+y’)
??
???
S.-K.Choi et al. (Belle) PRL100, 142001
R.Mizuk et al. (Belle) PRD 78,
072004
K3*(1780)
K*(1680)
K*(1400)’s
M2(K+p-)
K*(890)
K*(1430)K+p-?
K*(890)K+p-
M2(K+p-)
fit with a 2-body isobar model
Our default model
B
K*y’
ky’
K2*y’
K*(890)y’
Kpy’
(cc1)
K*(1410)y’ (cc1)
K0*(1430)y’ (cc1)
KZ+
Z+ p+ y’ (p+cc1)
with & without
K2*(1430)y’ (cc1)
K*(1680)y’ (cc1)
KZ+
BK p+ y’ results with no KZ+ term
2
1
12 3 4 5
C
R.Mizuk et al. (Belle) PRD 80, 031104
B
3
A
4
A
B
5
fit CL=0.1%
C
5
BK p+ y’ results with a KZ+ term
1
3
2
4
1
2
3
4
5
A
C
B
C
A
5
fit CL=36%
R.Mizuk et al. (Belle) PRD 80, 031104
B
BK
+
p
y’ Dalitz-plot fit results
K* veto applied
With Z(4430)
Significance: 6.4s
+9.6
-5
Bf (B 0 KZ + )  Bf (Z +  p +y ')  (3.2+1.8
)
10
-0.9 -1.6
No big contradiction
Without
Z(4430)
BaBar:
no confirmation

B. Aubert et al. (BaBar) PRD 79, 112001
Belle:
-5
= (3.2+1.8+9.6
0.9-1.6 )x10
Dalitz analysis of B0K-p+cc1
DE GeV
M2(p+cc1)
R.Mizuk et al. (Belle) PRD 78, 072004
???
K3*(1780)
K*(1680)
K*(1400)’s
M (J/yg) GeV
K*(890)
G
Fit model: all low-lying K*’s (no Z+ state)
a b c d
g
f
e
a
b
e
c
d
g
f
C.L.=310-10
R.Mizuk et al. (Belle) PRD 78, 072004
Fit model: all K*’s + one Z+ state
a b c d
g
f
e
a
b
e
c
d
g
f
C.L.=0.1%
R.Mizuk et al. (Belle)
PRD 78, 072004
Are there two?
?
?
M2(p+cc1)
?
a b c d
?
M2(p+cc1)
R.Mizuk et al. (Belle) PRD 78, 072004
Fit model: all K*’s + two Z+ states
a b c d
g
f
e
a
b
e
c
d
g
f
C.L.=42%
R.Mizuk et al. (Belle) PRD 78, 072004
Two Z-states give best fit
Projection with K* veto
R.Mizuk et al. (Belle) PRD 78, 072004 (2008)
BaBar doesn’t agree
J. Lees et al. (BaBar) PRD 85, 052003 (2012)
BaBar
K* +Z1+Z2
K* only
Conclusion:
no >2s evidence for
Z1 or Z2  p+ cc1, set upper limits:
Critique of the BaBar critique
constr. interf
BaBar
J. Lees et al. (BaBar) PRD 85, 052003 (2012)
Belle
R.Mizuk et al. (Belle) PRD 78, 072004 (2008)
Beautiful examples of charged
bottomonium-like mesons in
Roman Mizuk’s talk.
Summary
Lots of new particles found recently
low-lying charmonium/bottomonium states
- cc2, yc2, hb(1P), hb(2P), hb(1S),hb(2S),cb(3P),…
-all match potential model predictions well
X(3872) seems to be the cc1, charmonium state
with a large D0D*0 “molecular” component
-why is its mass right at the D0D*0 threshold?
_
_
Y(3915)w J/y properties reproduced by a VV
molecule-type model
-JPC=0++, but Y(3915)DD not seen
_
Clear examples of charged charmonium-like
(& bottomonium-like) states are seen
-Z(4430)p+y’; Z1(4050) & Z2(4250)p+cc1
- (in spite of what BaBar says!!)
Lots of evidence for molecules as opposed to
diquarks, etc…
_
_
Y(4660)
Lots of pieces
Y(4360)
Y(4260)
Does Y(3915)  DD ?
_
BKy(3770)
|
D0D0
68+15 events
BKD0D0
J. Brodzicka et al. (Belle) PRD 100, 092001
No signal
near 3940:
3915 MeV
<16 events
Use 16/68 & scale from PDG values:
Bf (B Ky")  Bf (y"D0 D 0 ) 1.6  0.4 10 -4
Bf (B KX 3915)  Bf (X 3915 wJ /y )  3 110-5
Bf (Y(3940) wJ /y )
0 0  0.75
Bf (Y(3940) D D )