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Evidence for Exotic Mesons
Belle
Workshop on light flavors & chiral dynamics北大 Sept 29-30,2007
Stephen OlsenU. of Hawai’i
&高能所 北京
BaBar
X(3
87
2)
Y(4
26
0)
X(3
94
0)
Y(3
94
0)
Y(4
32
5) Y
(4660)
X(4
160)
Y(4
008)
Y(4
78
0)
Z(4
43
0)
Talk outline
Constituent Quark Model(CQM)
(& 6 antiquarks)
Mesons: q q
c: c+2/3
c: C-2/3
+ : s-1/3
s+1/3
s+1/3
c-2/3
u-2/3
b+1//3
u+2/3
- : b-1/3
S=1/3
b+1/3
t-2/3c+2/3
b-1/3
t+2/3
6 quarks
Baryons: qqq
u-2/3
d+1/3 s+1/3
u+2/3
d-1/3 s-1/3
Gell-Mann
Zweig
Fabulously successful
mesons qq
QCD suggests non-qq meson spectroscopies
Glueballs:gluon-gluon color singlet states
Multi-quark mesons:molecules: diquark-antidiquark:
qq-gluon hybrid mesons
d c
dc
c c
d c
dc
Searching for non-QPM hadrons is a risky business
Remember the pentaquark
T.Nakano et al (LEPS) PRL 91 012002 (2003) 742 citations
+(1530)?
forget
You never can be sure:
or something else.
Is mother nature is smiling at you?
The XYZ mesons: candidates for non-qq states
c c
u cuc
4 quark candidates(from Belle)
“ hybrid” qq-gluon candidates(from Babar & Belle)
Charmonium is of particular interest
because it is an especially good system
to use to search for non-qq mesons
a cc meson has to fit into one of these slots:
If it doesn’t, it is a good candidate for a non qq meson
B-factories produce lots of cc pairs
0-+, 1- - or 1++
0-+, 0++, 2++
C =+ states
1- - only
Lots new on the “XYZ” particles
• X(3872)– J/ in BKJ/
• Z(3930)– DD in DD
• Y(3940)– J/ in BK J/
• X(3940)– e+e- J/X & e+e- J/ DD*
• Y(4260)– J/ in e+e- J/
• Y(4325)– +-’ in e+e-+-’
Y(4008)?
Y(4250)
Y(4370)
Y(4660)
X(3880)DD- e+e- J/ DD
X(4160)D*D*- e+e- J/ D*D*
Z+(4430)+ - BK+’
New Belle/BaBar results:(Summer 2007)
Status spring 2007:
confirmed by BaBar
updated by Belle
I’ll concentrate on recent results.
X(3872)
>300 citations
X(3872) properties (PDG2007)
MD0 + MD*0 = 3.871.8 ± 0.4
MeV
M() looks like
2/dof = 43/39 (CL=28%)
kinematiclimit≈m
PRL 96 102002
CDFBelle
• Belle & CDF: JPC = 1++ most likely
What’s new with the X(3872)?
BaBar confirms Belle’s DD threshold enhancement
Mass is 3.8±1.2 MeV above WAvg X(3872)J/ mass;
(~3is this significant?
Both groups see a high mass value
Belle’s BKSX & BK±X comparison
M = 0.22 ± 0.90 ± 0.27 MeV
KS mode K± mode
“molecular” modelspredicted this to be <<1(Braaten et al PRD 71 074005)
“diquark-antidiquark” modelspredicted this to be 8±3 MeV
(Maiani et al PRD 71 014028)
Confirms an earlier BaBar result
Is there a cc slot for the X(3872)?
3872 rJ/ too small
r(J/) too big
1++(c1’)
cJ/ ispin forbidden D0D00 @ thresh.suppressed BKcc(J=2) suppressed
2-+(c2)
Y(3940) in BK J/
M≈3940 ± 11 MeV≈ 92 ± 24 MeV
Belle PRL94, 182002 (2005)
M(J/) MeVM2(K) GeV2
M2(
J
) G
eV2
Y(3940) properties
Belle PRL94, 182002 (2005)
M(J/) MeV
(Y3940 J/ > 7 MeV (an SUF(3) violating decay)
~
this is 103 x (’ J/ (another SUF(3) violating decay)
if the Z(3930) is the c2’the Y(3940) mass is toohigh for it to be the c1’
Confirmed by BaBar this summer
B±K±J/ B±K±J/
B0KSJ/
M2(K)
J)
ratio
Some discrepancy in M & ; general features agree
G.CibinettoEPS-2007
Is there a cc slot for Y(3940) ?
Can M(c1’)>M(c2’)?c1’
Mass is lowc”
“ “ “ “c0
’
39403931
For any charmonium assignment, [Y(3940) J/ is too large.
Belle updates e+e-J/D(*)D(*)
D(*)
Use “partial reconstruction technique”
reconstructthese
J/
D(*)
“Recoil” D(*) undetected(inferred fromkinematics)
Continuum
e+ e
-
annihila
tion
e+ e-
J/D(*) recoil mass
J/
DD
J/
DD
*
J/
D*D
*
J/
DD
*
Partial reconstruction
reconstruct
Belle arXiv:0708.3812
M(DD*): Confirm X(3940)DD*
D-reconstructed D*-tag
D sidebands
6.0
Bg subtracted
M = 3942 +7 ± 6 MeV
tot = 37 +26 ±12 MeV
Nsig =52 +24 ± 11evts
-6
-15
-16
Previous values:M = (3943 ± 6 ± 6) MeV = (15.4 10.1) MeV< 52 MeV at 90%CL
PRL 98, 802001 (2007)
arXiv:0708.3812
Is there a cc slot for X(3940) ?
Mass is > M(c2’) &no c1 recoil seen
c1’
Mass is ~ 60 MeV low(if (3S) = (4040))c”
c0
’
39403931
Mass is > M(c2’) &DD decays not seen
Maybe the c”
M(DD): Broad threshold enhancement
arXiv:0708.3812
Relativistic BW
D sidebands
D-reconstructed D-tag
3.8
Bg subtracted
Resonance?Thresh effect?… ?
M(D*D*)a new state at ~4160 MeV
D*-reconstructed + D*-tag
5.5
M = 4156 +25 ± 15 MeV
tot = 139 +111 ± 21MeV
Nsig =24 +12 ± 11evts
-20
-61
-8
arXiv:0708.3812
It has to have C=+; most likely 0-+,... possibly 0++
if 0++, why is it
not seen in DD
A cc assignment for X(4160) ?
Mass is far too low(unless (4S)=(4160),but, then, where is (2D?))
c’’’
Mass is too high(if (3S)=(4040))
or too low(if (3S) = (4160))
c”
39403931
Can place either theX(3940) or X(4160),but probably not both.
The 1-- states seen in ISR
e+e- isr Y(4260) at BaBar
233 fb-1
Y(4260)
BaBar PRL95, 142001 (2005)
~50pb
M=4259 8 +2 MeV
= 88 23 +6 MeV -6
-9
fitted values:
Not seen in e+e- hadrons
(Y4260 J/) > 1.6MeV @ 90% CL
X.H. Mo et al, PL B640, 182 (2006)
4260
4260
BES data
~3nb
peakY(4260)+J/pb
Huge by charm
onium
standards
“Y(4260)” at Belle (New) M=4247 12 +17 MeV
= 108 19 ±10 MeV -32
M=4008 40 +114 MeV
= 226 44 ±87 MeV -28
???
C.Z Yuan et al (Belle) arXiv:0707.2541To appear in PRL
M=4259 8 +2 MeV
= 88 23 +6 MeV -6
-9
BaBar values:
Resonance?Thresh effect?…?
M() near 4008 & 4260 MeV
3.8 < M(J/) <4.2 GeV 4.2 < M(J/) <4.4 GeV
No 1-- cc slot for the Y(4260)
42804260
X.H. Mo et al, hep-ex/0603024
Is the Y(4260) a cc-gluon hybrid?
c c
• qq-gluon excitations predicted 30 yrs ago • lowest 1-- cc-gluon mass expected at ~4.3 GeV • relevant open charm threshold is D**D (~4.28 GeV) • (J/) larger than that for normal charmonium • (e+e-) smaller than that for ordinary charmonium
Horn & Mandula PRD 17, 898 (1977)
Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, 15713 (2003)
Isgur, Koloski & Paton PRL 54, 869 (1985)
McNeile, Michael & Pennanen PRD 65, 094505 (2002)
Close & Page NP B443, 233 (1995)
Y(4260) s
eems t
o matc
h all
of these
!!!
DD** thresholds in & “Y(4260)”
4.28-mD
D** spectrum
M(J/) GeV
No obviousdistortions
D1D
D2D
BaBar ’ peak at 4325MeV
Nbkg = 3.1 1.0
Nevt = 68 (<5.7 GeV/c2)
2-prob < 5.7 GeV/c2
Y(4260) 6.5 10-3
(4415) 1.2 10-13
Y(4320) 29%
e+e-ISR ’
M=4324 24 MeV
= 172 33 MeV
above all D**D thresholds
S.W.Ye QWG-2006 June 2006
Not Compatible with the Y(4260)
D1D
D2D
298 fb-1 (BaBar) hep-ex/0610057
BaBar PRL 98 252001 (2007)
4325 MeV ’ peak in Belle (new)
M=4324 24 MeV
= 172 33 MeV
548 fb-1
X.L. Wang et al (Belle) arXiv:0707.3699
Two peaks!
M=4664 11 ±5 MeV
= 48 15 ±3 MeV
M=4361 9 ±9 MeV
= 74 15 ±10 MeV
BaBar values
(both relatively narrow)(& both above D**D thresh)
(& neither consistent with 4260)
4260
Y(4660) f0(980) ’?
4.0 < M(’) <4.5 GeV 4.5 < M(’) <4.9 GeV
f0(980)?
K+K- J/ from Belle (very new)
C.Z.Yuan et al (Belle) arXiv:0709.2565
(4415)?
M=4875 132 MeV
= 630 126 MeV M=4430 +38 MeV
= 254 +55 MeV
4260
-43
-46
M(K+K-)
Latest Newsele
ctric
ally
charg
ed!!
M(±’) from BK ±’
M2(K) GeV2
M2(’)
GeV
2
K. Abe et al (Belle) arXiv:0708.1790
K*KK2*K Veto Veto
M(’) GeV
6.5
M = 4433 ±4 ±1 MeV
tot = 45 +17 +30 MeV
Nsig =124 ± 31evts-13 -11
Could this be a reflectionfrom the K channel?
Cos vs M2(’)
16 GeV2
22 GeV2
M2(
’)
+1.0
-1.0
cos
M (’) & cosare tightly correlated;a peak in cos peak in M(’)
(4.43)2GeV2 0.25
’
K
Can interference between K partial waves produce a peak?
Only S-, P- and D-waves seen in data
inte
rfere
Add incoherently
Can we make a peak at cos≈0.25
with only S-, P- & D-waves?
Not without introducing other, even more dramatic
features at other cos (&,, other M’) values.
Comments on the Z+(4430)
Not a reflection from the K system~
No significant signal in B KJ/
It has non-zero charge not cc or hybrid
Mass, width & decay pattern similar to Y(4360) & Y(4660)
conclusions• There seems to be a new hadron spectroscopy in the M=3.5~5
GeV region– Maybe more than one– Bodes well for BESIII, Super-B factories & PANDA
• Some states are narrow even though they are far above decay thresholds
– e.g. Y(4660)’ & Z+(4430)’ have large Q but ≈50 MeV
• characterized by large partial widths (Bfs) to hadrons+J/(or ’)
– Br(X(3872)J/) > 4.3% (Isospin=1)– (Y(3940)J/) > 7 MeV (SU(3) octet)– (Y(4260)J/) > 1.6 MeV
• States that decay to ’ not seen decaying to J/ (and vice-versa) – Bf(Y(4660)’) >> Bf(y(4660)J/) same for Y(4360) & Z(4430’– Y(4260) not seen in Y(4260)’
• The new 1-- states are not apparent in the e+e-D(*)D(*) cross sections
• There is no evident transitions at the D**D mass threshold
(mine)
New 1-- states J/
J/
’
some of the states are near thresholds,but this is not a universal feature
DSDS thresholdsDD thresholds
D*D*
DD*
DD
tot
Y(4
660)
Y(4
360)
Y(4
260)
Y(4
008) The 1-- states
do not match wellto peaks in hadr.
cross-sections
Pakhlova (Belle) PRL 98, 092001 (2007)
Lots of pieces
Y(4360)
Y(4
660)
Y(4260)
Y(4
008)
X(3872)
X(3940
)
X(416
0
)
Z(4430) Y(3940)
Are the
y al
l fro
m the
sam
e pu
zzle
?
謝謝
Inclusive BKx from BaBar
?
Fully reconstructed B- tags
M2(’) / cos plot1.0< M(K)<1.4 GeV
Our attempts to fit theM=4.43 GeV (cos=0.25)
peak with any combination ofS-, P- & D-waves
BaBar looked for a charged partner of the X(3872) and excluded isospin 1: BF(B0 X- K+ ) BF(X J/ψ - 0 ) < 5.4 x 10-6
BF(B- X- K0 ) BF(X J/ψ - 0 ) < 2.2 x 10-5
c.f BF(B0 X0 K+ ) BF(X 0 J/ψ -- + ) =(1.28 0.41 ) x 10-5