Searches for exotic mesons
Stephen L. Olsen University of Hawai’i
DOE site visit Aug 22, 2005
c c
ud
uud
u
u cuc•Multi-quark molecules
•qq-gluon hybrids
•baryonium
Probe QCD from other directions
non-qq or non-qqq hadron spectroscopies:
Reawakened by the claims for Pentaquarks
e.g. an S=+1 baryon
ud
usd
Pentaquarks?“Seen” in many experiments
BaBar
High interest:1st pentaquark paperhas >500 citations
BelleBES
but not seen in just as many others
CDF
Compass
Jlab p
Pentaquark Scoreboard
Positive signals Negative results
Also: Belle Compass L3 Jlab(CLAS) (pK+Ksn)
Yes: 17 No: 18
This talk
• Searches for non-standard mesons with hidden charm at Belle
• Search for baryonium mesons at BES
c cu cuc
ud
uud
u
searches for non-standard mesons with “hidden charm” at Belle
• standard cc mesons are:– best understood theoretically– narrow & non overlapping
• c + c systems are commonly produced in B meson decays.
b
cc
s
Vcb
cosC
CKM favored
W-
c c
u cuc
(i.e containing c & c)
Its existence is well established
seen in 4 experiments
X(3872)
CDF
X(3872)
D0
hep-ex/0406022
9.411.6
no obvious cc assignment
3872
c”
hc’
c1’
2
c2
3
M too low and too small
angular dist’n rules out 1
J/ way too small
c too small;M() wrong
c& DD) too small
c should dominate
SLO hep-ex/0407033
JPC possibilities (for J ≤ 2)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
JPC possibilities0-- ruled out; JP=0+,1- & 2+ unlikely
0--
exotic
violates parity 0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
Strong evidence for C=+1
13.6 ± 4.4 X(3872)J/evts (>4significance)
X(3872)J/
virtual (782)?
X(3872)J/
Bf(XJ/)
Bf(XJ/)=0.14 ± 0.05
Br(X3J/)Br(X2J/) = 1.0 ± 0.5
M()
M()
X(3872)J/
Fits to (760)
JPC possibilities (C=-1 ruled out)
0--
exotic
Violates parity 0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S)) 1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2) 2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
Angular Correlations
K
J/
J=0J=0X3872
Jz=0
z
Rosner (PRD 70 094023)
Bugg (PRD 71 016006)
Suzuki, Pakvasa (PLB 579 67)
JPC possibilities (0-+ & 0++ ruled out)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S)) 1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2) 2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
M() can distinguish -J/ S- & P-waves
S-wave: 2/dof = 43/39 P-wave: 2/dof = 71/39
q*roll-off
q*3
roll-off
(CL=0.1%)(CL= 28%)
Shape of M() distribution nearthe kinematic limit favors S-wave
Possible JPC values (J-+ ruled out)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2) 2++
DD allowed
c2’)
2+-
exotic
DD allowed
X(3872) D0D00 ?
11.3±3.6 sig.evts (>4)
Bf(BKX)Bf(XDD)=2.2±0.7±0.4x10-4
D*0D00?
M(D0D00)
• 1++ : DD* in an S-wave q*
• 2++ : DD in a D-wave q*5
Strong threshold suppression
Possible JPC values (2++ ruled out)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
1++1++
can it be a 1++ cc state?
1++c1’
3872
Mass is too low
Bf(XJ/)>4%
is too large(Isospin
forbidden)
c1’ component of X(3872) is ≤ few%
Intriguing fact
MX3872 =3872 ± 0.6 ± 0.5 MeV
mD0 + m D0* = 3871.2 ± 1.0 MeV
lowest masscharmed meson
lowest mass spin=1charmed meson
D D*
2 loosely bound qq color singlets
with M = mD + mD* -
u
cu
c
one exchangeattractive for 1++ Tornqvist PLB 590, 209 (2004)
Deuson? deuteron-like DD* bound state?
X(3872) = D0D*0 bound state?
• JPC = 1++ is favored
• M ≈ mD0 + mD0*
• Large isospin violation is natural (& was predicted):
|D0D*0> = 1/2(|10> - |00>)
• (XJ/) < (XJ/) was predicted
• (XD0D00) too large?
Equal mixture of I=1 & I =0
Swanson PLB 598, 197 (2004)
Tornqvist PLB 590, 209 (2004)
Swanson PLB 588, 189 (2004)
X(3872) conclusion
•JPC = 1++
•cc content is small
•matches most expectations for a D0D*0 bound state
C C
u cuca non-qq meson
Are there others?Is the X(3872) a one-of-a-kind curiousity?
or the 1st entry in a new spectroscopy?
Look at other B decays hadrons+J/
BK J/
BK J/
BK J/
BK J/ in Belle
“Y(3940)”M≈3940 ± 11 MeV≈ 92 ± 24 MeV
Mbc Mbc Mbc
S.K. Choi & S.L.Olsen et al.(Belle), PRL94, 182002 (2005)
M(J/) MeV
Y(3940): What is it?
• Charmonium?– Conventional wisdom: J/ should not be
a discovery mode for a cc state with mass above DD & DD* threshold!
• Some kind of -J/ threshold interaction?– the J/is not surrounded by brown
muck; can it act like an ordinary hadron?
J/
Brambilla et al (QWG) hep-ph/0412158
Y(3940): What is it (cont’d)?
• another tetraquark?– M ≈ 2mDs
– not seen in YJ/• ( contains ss)
– width too large??– no exchange for DSDS
s csc
??PRL 93, 041801
M( J/)
Y(3940): What is it (cont’d) ?
• cc-gluon hybrid?– predicted by QCD,– decays to DD and DD* are suppressed (“open-charm” thresh = mD + m D** = 4.3 GeV)
– large hadron+J/ widths are predicted– masses expected to be 4.3 ~ 4.4 GeV
(higher than what we see)
c c
Horn & Mandula PRD 17 898 (1974) + (many) others
BaBar’s Y(4260)
)or ( /ISR eeJ/ψJee
211 fb-1 data collected at √(s) = 10.58 GeV
(2S) Y(4260)
11802110 (2S) evts12523 Y(4260) evts
J/ sideband
Well above DD & DD* threshold but found in an OZI-suppressed mode??
M=4259 8 MeV
= 88 23 MeV
B. Aubert et al. (BaBar)hep-ph/0506081
cc summary• X(3872):
– JPC established as 1++
– cc component is small (≤ few %)– all properties consistent with a D0D*0
bound stateu cuc
a non-standard meson
• Y(3940) Belle, Y(4260) BaBar
c c
?????
- Lots to do: determine JPC ; find other modes (DD*, DsDs, …?)
Hardronic charmonium transitions
(’J/) 70 keV
(”J/) 50 keV
(’J/) 5 keVSUF(3) violating
HW (for theorists):How can (Y3940)J/)and (Y(4260)J/)be ~1000x larger?
J/ pp (at BES)
M(pp)
M(pp)-2mp (GeV)
0 0.1 0.2 0.3
M=1859 MeV/c2
< 30 MeV/c2 (90% CL)
+3 +510 25
3-body phase space
acceptance weighted BW
Phys. Rev. Lett. 91, 022001 (2003)
Baryonium potential & Wave fcn
X ’ should be a strong channel
-V0(r)
Potentialbarrier
G.J. Dung & M.L. Yan hep-ph/0502127
“Rectangularized”Skyrmion-type
potentialI = 0, Jpc=0-+
pp annihilationM ~ 1860 MeV ~ 16 MeV large
uncertainties
M(’) from J/ ’
54264obsN
410)4.04.02.2()()( XBXJB
7.7The +- mass spectrum for decaying into +- and
BESII Preliminary
59.18.0 10)4.00.7()()(:..
ppXBXJBfc
M = 183463 MeV = 68 20 8 MeV
Re-fit to J/p p including FSI
Include FSI curve from A.Sirbirtsev et al. ( Phys.Rev.D71:054010, 2005 ) in the fit (I=0)
M = 1830.6 6.7 MeV
= < 153 MeV @90%C.L.
ppp mM 2In good agreement
with X(1835)
_
• c2,c0<<c1•X(3872) production much lower than for other Charmonium states:•can set lower limit on B.F.
Can measure absolute B.F.’s of B-K-X0
e+e-B+B-
K-X0
Lower limit on BF(XJ/) > 4.3% @ 90% C.L
244 fb-1
Very clear J/ and c signals N J/=258+- 42N c =266 +-42
c2 c1 c0
J/
Jon ColemanMoriond-QCDMarch 2005
Kinematic variables
CM energy difference:
Beam-constrained mass:
2/
2 )()2( JKCMbc ppEm
BK J
BKJ2// cmJK EEEE
B
Bϒ(4S)
Ecm/2
e e
Ecm/2
Mbc
E
1++
l
1++: sin2l sin2
K
1++ looks okay!
compute angles inX(3872) restframe
|cosl|
2/dof = 11/9
|cos|
2/dof = 5/9