Transcript Slide 1

The XYZ mesons
Stephen L. Olsen
University of Hawaii
PANIC-08 Nov 10-14, 2008 Eilat
X(3872)
(Decay to final
states with a cc
pair & Sqi=0 )
X & Y mesons
BK p+p-J/y
Y(4260)
Belle
BaBar
e+e-gISRp+p-J/y
Belle
M(p+p-J/y)-M(J/y)
Belle
Y(3940)
M(p+p-J/y)
BaBar
BK wJ/y
Y(4350) & Y(4460)
BaBar
M(wJ/y)
e+e-gISRp+p-y’
Belle
M(wJ/y)
X(3940)
e+e-DD*J/y
M(p+p-y’)
X(4160)
e+e-D*D*J/y
Belle
e+e-gISRLcLc
Belle
Belle
M(DD*)
M(D*D*)
M(LcLc)
Neutral cc X & Y mesons
Name
JPC
G (MeV)
Decay modes
Expts
comment
X(3872)
1++
<2.3
ppJ/y; gJ/y; DD*
Belle/CDF/D0/BaBar
DD* molecule?
X(3940)
0?+
~37
DD*
(not DD, wJ/y)
Belle
hc’’(?)
Y(3940)
??+
~30
(not DD*)
Belle/BaBar
X(4160)
0?+
~140
(not DD, DD*)
Belle
Y(4008)
1--
~225
ppJ/y
Belle
Y(4260)
1--
~80
ppJ/y (not ppy’)
BaBar/CLEO/Belle
Y(4350)
1--
~75
ppy’
Y(4660)
1--
~50
ppy’; LcLc (?)
wJ/y
D*D*
(not ppJ/y)
hc’’(?)
ccg hybrid?
BaBar/Belle
Belle
@LcLc threshold
Are any of these standard cc charmonium?
predicted
measured
Is the 1++ X(3872) the cc1’ (23P1) ?
??
3872MeV
• Mass is too low
•
cc1’ppJ/y
violates Ispin
•Bf(X3872ppJ/y)>4%
• G(gJ/y) should be >>G(rJ/y)
•expt: G(gJ/y) <<G(rJ/y)
Neutral cc X & Y mesons
Name
JPC
G (MeV)
Decay modes
Expts
comment
X(3872)
1++
<2.3
ppJ/y; gJ/y; DD*
Belle/CDF/D0/BaBar
DD* molecule?
X(3940)
0?+
~37
DD*
(not DD, wJ/y)
Belle
hc’’(?)
Y(3940)
??+
~30
(not DD*)
Belle/BaBar
X(4160)
0?+
~140
(not DD)
Belle
Y(4008)
1--
~225
ppJ/y
Belle
Y(4260)
1--
~80
ppJ/y
BaBar/CLEO/Belle
Y(4350)
1--
~75
ppy’
BaBar/Belle
Y(4660)
1--
~50
ppy’; LcLc (?)
Belle
wJ/y
D*D*
hc’’(?)
ccg hybrid?
@LcLc threshold
It is pretty widely --but not universally-- accepted that the X(3872)
is not a standard cc charmonium state. For a dissenting view, see
C Meng & KT Chao PRD 75,114002 (2007)
Could the Y(3940) be charmonium?
Bf(BKY3940)xBf(Y3940wJ/y)
G(MeV)
Belle
(7.1 ± 3.1) x 10-5
87±34
BaBar
Avg
(4.9 ± 1.1) x 10-5
(5.2 ± 1.0) x 10-5
33±12
39±11
assuming Bf(BKY3940)<Bf(BKJ/y)
G(Y3940wJ/y)>1MeV
= 1.0x10-3
Neutral cc X & Y mesons
Name
JPC
G (MeV)
Decay modes
Expts
comment
X(3872)
1++
<2.3
ppJ/y; gJ/y; DD*
Belle/CDF/D0/BaBar
DD* molecule?
X(3940)
0?+
~37
DD*
(not DD, wJ/y)
Belle
hc’’(?)
Y(3940)
??+
~30
(not DD*)
Belle/BaBar
X(4160)
0?+
~140
(not DD)
Belle
Y(4008)
1--
~225
ppJ/y
Belle
Y(4260)
1--
~80
ppJ/y
BaBar/CLEO/Belle
Y(4350)
1--
~75
ppy’
BaBar/Belle
Y(4660)
1--
~50
ppy’; LcLc (?)
Belle
wJ/y
D*D*
hc’’(?)
ccg hybrid?
@LcLc threshold
X(3940) & X(4160) = hc” &/or hc’’’ ?
hc’’’
4160MeV
3940MeV
h c”
One, or the other, could be the hc”, but it seems very
unlikely that one is the hc” and the other is the hc’’’
Neutral cc X & Y mesons
Name
JPC
G (MeV)
Decay modes
Expts
comment
X(3872)
1++
<2.3
ppJ/y; gJ/y; DD*
Belle/CDF/D0/BaBar
DD* molecule?
?????
X(3940)
0?+
~37
DD*
(not DD, wJ/y)
Belle
hc’’(?)
Y(3940)
??+
~30
(not DD*)
Belle/BaBar
?????
X(4160)
0?+
~140
(not DD)
Belle
Y(4008)
1--
~225
ppJ/y
Belle
Y(4260)
1--
~80
ppJ/y
BaBar/CLEO/Belle
Y(4350)
1--
~75
ppy’
BaBar/Belle
Y(4660)
1--
~50
ppy’; LcLc (?)
Belle
wJ/y
D*D*
hc’’(?)
ccg hybrid?
@LcLc threshold
1-- ISR Y states not seen in D(*)D(*)
G.Pakhlova et al (Belle):
σ(e+e–→open charm)
DDπ
PRL 101,172001
Λc+Λc–
Y(4660)
y(4415)
Y(4260)
y(4040)
y(4415)
PRL 98,092001
D*D*
Y(4350)
y(4160)
Y(4008)
Y(4350)
D
D*
Y(466
0)
PRL 100,062001
Y(4260)
y(4040)
Y(4008)
?
y(4160)
DD
Belle: Sum of all measured exclusive contributions
y(3770)
PRD 77, 01103
Durham Data Base
if Ruds=2.285±0.03
This means that the ISR Y states
have G(ppJ/y(y’)) > 1 MeV
only 1 unassigned 1-- cc slot
Neutral cc X & Y mesons
Name
JPC
G (MeV)
Decay modes
Expts
comment
X(3872)
1++
<2.3
ppJ/y; gJ/y; DD*
Belle/CDF/D0/BaBar
DD* molecule?
?????
X(3940)
0?+
~37
DD*
(not DD, wJ/y)
Belle
hc’’(?)
Y(3940)
??+
~30
(not DD*)
Belle/BaBar
?????
X(4160)
0?+
~140
(not DD)
Belle
Y(4008)
1--
~225
ppJ/y
Belle
Y(4260)
1--
~80
ppJ/y
BaBar/CLEO/Belle
Y(4350)
1--
~75
ppy’
BaBar/Belle
Y(4660)
?????
1--
~50
ppy’; LcLc (?)
Belle
wJ/y
D*D*
hc’’(?)
ccg hybrid?
@LcLc threshold
At most 1 of the 1-- Y states can be conventional cc charmonium
The Z mesons
Electrically charged counterparts
of the X & Y mesons
The Z meson candidates
6.5 
M(p±y’) GeV
Z(4430)
M2(p±y’) GeV2
BK p+y’
S.-K. Choi et al (Belle) PRl 100, 142001
Z1(4050)
GeV2
Z2(4250)
M2(p±c’c1)
>6 
M(p±cc1) GeV
BK p+cc1
M2(Kp’) GeV2
M2(Kp’) GeV2
R.Mizuk,R.Chistov et al (Belle) PRD 78, 072004
Z meson properties
Name
Z(4430)
Mass(MeV)
4433±5
Width(MeV)
45+35-18
Decay mode
Z1(4050)
4051+24-43
82+51-29
p+cc1
Z2(4250)
4248+185-45
177+320-72
p+cc1
Can’t be cc charmonium
minimal quark content:
ccud
p+y’
d c
c u
Still controversial
Z(4430) not confirmed by BaBar
(but neither do they rule it out).
Belle
BaBar
Arafat Gabareen Mokhtar
talk at ICHEP-2008
B.Aubert et al (BaBar) arXiv/0811.0564
What could they
XYZ states be?
suggested possibilities
(some references in backup slides)
π c
c
u
u
u
D(*)D(*) molecules
(real or virtual)
masses should be near
M(D(*))+M(D(*)) mass
thresholds
Favored model for X3872
M(D0)+M(D*0)=3871.8±0.4
M(X3872)=3871.4±0.4
c
c u
c
c
g
diquark-diantiquarks
cc-gluon hybrids
Expect SU(3) multiplets
LQCD: M>~4.3 GeV
Open charm thresh
=MD+MD** 4285
(above Y4260 peak)
Non-zero charges
are not allowed
Thresholds
D(*)D(*)
( ) ( )
D*SDS*
??
No p exchng for DSDS
some of the states are near thresholds,
but this is not a universal feature
no evidence for multiplet partners
diquark-diantiquark expectations:
Xu(3872)
u c
c u
B+K-Xu
X+(3872)
Xd(3872)
u c
c d
d c
c d
B0K0X
d c
c u
Expect:
d
M(Xd)-M(Xu)= 2(md-mu)/cosq
 8 ± 3 MeV
L Maiani et al PRD 71,014028 (20050
X-(3872)
Bf(B0K-X+)Bf(X+p+p0J/y)
Bf(B-K-X0)Bf(X+p+p-J/y)
≈2
no X±(3872) isospin partner is
seen
B0  K± p∓ p0J/y
?
B∓  KS p∓ p0J/y
BaBar
?
Bf(B0K-X+)Bf(X+p+p0J/y)
Bf(B-K-X0)Bf(X+p+p-J/y)
BaBar
< 0.4
(expect  2)
B. Aubert et al (BaBar) PRD 71, 031501
B0KSXd & BK±Xu with Xu=Xd?
BaBar, arXiv: 0803.2838
BaBar
Belle
K± mode
Belle
BaBar
K± mode
KS mode
KS mode
DM = 0.22 ± 0.90 ± 0.27 MeV
Compared to 8±3 MeV
DM = 2.7 ± 1.6 ± 0.4 MeV
(Maiani et al PRD 71 014028)
What about in the X3872DD*
channel?
PRL 97,162002,2006
PRD77,011102,2008
NEW
6.4σ
4.9σ
B+& B0 D0D*0K
B K D0D0p0
+0.9
M=3875.2±0.7 -1.8
~2 higher than
M in ppJ/y mode
347fb-1
M=3875.1
Is this Maiani et al’s
partner particle?
+0.7
±0.5
-0.5
~4 higher than
M in ppJ/y mode
New results on X3872DD* from
Belle
B K D0D*0
D*→D0π0
D*→Dγ
More details in
Tagir Aushev’s talk
@ this meeting
605 fb-1
Flatte vs BW similar result: 8.8σ
M=3872.6
+0.5
±0.4 MeV
-0.4
N.Zwahlen, T.Aushev et al (Belle) arXiv/0810.0358
How about cc-gluon hybrids?
c
c
• qq-gluon excitations predicted 30 yrs ago
Horn & Mandula PRD 17, 898 (1977)
• LQCD: lowest 1-- cc-gluon mass ~4.3 GeV
Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, 15713 (2003)
- QCD sum rules get lower values ~3.7 GeV
Kisslinger et al, arXiv 0805.1943 (2008)
• relevant open charm threshold is D**D (~4.28 GeV)
Isgur, Koloski & Paton PRL 54, 869 (1985)
• G(ppJ/y) larger than that for normal charmonium
McNeile, Michael & Pennanen PRD 65, 094505 (2002)
• G(e+e-) for 1-- states less than ordinary charmonium
Close & Page NP B443, 233 (1995)
DD** thresholds and the
Y(4260), Y(4360) & Y(4660)
D
4.36-
D
4.26- 4.28-
3.883.85-
D
DD
Y(4360) & Y(4660) well above all
DD** thresholds
D
D
4285
4.66-
Belle
Scoreboard
candidate
Molecule?
cq cq
cc-gluon
X(3872)
X(3940)
??
Y(3940)
??
X(4160)
??
Y(4008)
??
Y(4260)
??
Y(4350)
??
Y(4660)
??
Z(4430)
??
Z1(4050)
??
Z2(4250)
??
??
No model can accommodate all
Are there XYZ counterparts in
the b- and s-quark sectors?
Y(4260) equivalent with b-quarks?
Belle
(e+e-  p+p- (nS))
Peaks not consistent with known bb states
G(pp(nS) ~ 1000x too large for bottomonium
K.F. Chen et al (Belle) arXiv:0808.2445
Y(4260) equivalent with s-quarks?
e+e-  g f0(980)f
(e+e-

p+p-
f(1020))
Y(2175)f0(980)f
BaBar
f0(980)p+p-
M(f0(980)f)
Confirmed by BES & Belle
confirmed by BESII
in J/y  h f f0(980)
BES
(e+e-  f0(980)f(1020))
Belle
M(f0(980)f GeV
X.L. Wang et al (Belle) arXiv: 0808.0006
M.Ablikim et al (BES)
PRL 100, 102003 (2008)
Maybe the X(1835) is one too?
J/ygX(1835)
|
 p+p-h’
X(1835)
M. Ablikim et al (BESII), Phys.Rev.Lett.95:262001,2005
BES
Concluding remarks
• A number of “mysterious” mesons have been observed
• They have large hadron-charmonium partial widths
– Much larger than those seen in the charmonium system
• There is no strong variations above DD** thresholds
– As expected for cc-gluon hybrids
• Some are near thresholds but not all
– As expected for molecules, threshold cusps, etc.
• No Isospin or SU(3) multiplet partners yet seen
– As expected for diquark-diantiquark models
• Similar structures in b- & (maybe) s-quark sectors
However, none of the proposed models have produced
a compelling match to the experimental observations
Y(4660)
Lots of pieces
Y(4360)
Y(4260)
Thank you
Backup Slides
Some recent reviews
• Galina Pakhlova arXix:0810.4114
– This includes 64 references
– See slides from her plenary talk @ ICHEP08
• S.-K. Choi arXiv:0810:3546
– See slides from her parallel talk @ ICHEP08
• E. Braaten arXiv:0808.2948
– 48 references, mostly on molecular-like models
• S. Godfrey & S.L.O. arXix:0801.3867
– 128 references, but almost a year old
Some theory references
•L Maiani et al
PRD 71,014028 (2005)
c c
cc1’ charmonium?
•T-W Chiu & TH Hsieh
•C Meng & KT Chao
PRD 75,114002 (2007)
PRD 73, 111503 (2006)
•D Ebert et al
PLB 634, 214 (2006)
•H Lipkin & M Karliner
PLB 638, 221 (2006)
…
•NA Tornqvist
PLB 590, 209 (2004)
•ES Swanson
PLB 598,197 (2004)
•E Braaten & T Kusunoki
PRD 69 074005 (2004)
•CY Wong
PRC 69, 055202 (2004)
•MB Voloshin
PLB 579, 316 (2004)
•F Close & P Page
…
PLB 578,119 (2004)
too light??
P Lacock et al (UKQCD)
PLB 401, 308 (1997)
B-factories produce lots of cc pairs
0-+, 1- - or 1++
0-+, 0++, 2++
1- - only
C =+ states