Transcript Heavy Quarkonium Spectroscopy

Heavy Quarkonium
Spectroscopy
Riccardo Faccini
University “La Sapienza” and INFN Rome
Roma, 2 ottobre 2007
[tratto dal talk ad LP’07]
Only charmonium and bottomonium considered here
Quarkonium for Pedestrians

Quarkonium is a bound state of a quark and an
antiquark


Relevant quantum numbers: n,L,S,J
Relationship with Parity and Charge Conj:



Not all JPC allowed (e.g. 0+-,0--,1-+,2+- forbidden)
Decay Properties:



P=(-1)L+1, C=(-1)L+S
Below open quark threshold (e.g. (cc)DD) only
electromagnetic or as suppressed decays allowed  mostly
narrow states
Above open quark threshold (if DD decays allowed) mostly
broad states
What can we learn?

Understanding of QCD:


‘regular quarkonium’  tests of NRQCD, potential models, …
‘new states’  new forms of aggregations mediated by the strong
interactions
Charmonium: state of the art
M(MeV)
(2S+1)L
same JPC as
J/y but
mostly D
wave !
J
y(4160)
Increasing L 
Open charm thr.
h’c y’ c
c2
Recent acquisitions
hc
J/y
cc1
Increasing n 
y(4040)
y(3770)
hc
cc0
(pot. Models)
QWG: hep-ph/0412158
JPC
Basically all states below the open charm threshold are observed and explained
Bottomonium: state of the art
Open bottom thr.
Y(3S)
Y(2S)
Unconfirmed J
assignments of
all the cb s
Y(1S)
c(2P)b{2,1,0}
2 hb and 3 D
wave states are
narrow but not
observed
Increasing L 
Y(1D)
c(1P)b{2,1,0}
(pot. Models)
QWG: hep-ph/0412158
8 narrow resonances still missing !
Increasing n 
hb (x3)
completely
missing
Beyond the quarkonium

Search for states with 2 quarks+”something else”



Hybrids: qq+n gluons



Lowest state 1-+ (forbidden for quarkonium)
Dominant decay HDD**
Search for resonances:
Tetraquarks: [qq’][qq’]



New forms of aggregation
Expected but never identified!!!
Large amount of states
small widths also above threshold
Molecules: M[qq]M[q’q’]

• with non-quarkonium JPC
• unnaturally small widths
• not null charge: would be clear
indication of something new going
on
Smaller number of states but still small widths also above threshold
Measuring the quantum numbers
e+
gISR
X

Production:



e-
ISR only produces with same quantum numbers as the photon
(JPC=1--)
gg only produces with C=+
e+
+
Double charmonium production
e
e+e-  g*Xcc1Xcc2
Possible only if quantum numbers of the two
charmonia can be combined to give a 1--.

Decay:


X
e-
e-
Angular distributions of decay products depend on JP.
Selection rules


Conservation of J
Conservation of P,C in strong and e.m. decays
Samples used in results
Experiments
58MJ/y, 14M y(2S)

e+e- Charmonium (CLEO-c, BES-II)



L~1033/cm2/s
E=3.0-4.3 GeV
657M Y(4S)
e+e-  Y(4S): (BaBar, Belle, CLEO)


383M Y(4S) 1.5M Y(1S),1.9M Y(2S),
1.7M Y(3S),9M Y(4S)
L~1034/cm2/s
Charmonium in B decays, ISR and gg production


3M y(2S), 1.8 M y(3770)
Capability to measure JPC also in production
pp colliders (CDF, D0)
-1
800pb-1 1.3 fb


High Xsection  copious production
Disclamers:
Extremely high backgrounds
• time is very short
 could not cover everything
• theory statements are indicative
Quarkonium Spectroscopy
Updates on 1-- charmonium states
arXiv:0705.4500
Belle-CONF-0771
DD*2(2460)
~14σ
DD not DD*2(2460)
improved measurements, including
interference for the first time!!!
MeV
y(3770)
y(4040)
y(4160) y(4415)
M
3771±2
4039±5
4192±6
4415±8
G
25±7
81±14
73±15
73±21
CLEO-c observes y(3770)cc0g
Confirms 3D assignment [hep-ex/0605070]
First exclusive decay observed:
DD*2(2460) [dominant]

3D
1
candidate
Y(nS)Y(mS) transitions
The issue:
 Quarkonium transitions between 3S1 states described
by the QCD Multipole Expansion




Data on Charmonium transitions well fitted by
predictions


Tests heavy quark and low energy hadronic systems
BR(X(nS)X(mS)h)/ BR(X(nS)X(mS))
 invariant mass spectra  simplest PCAC matrix element
expects enhancement at high masses
Bottomonium physics richer because of larger phase-space
Y(2S) and Y(3S) transitions known for years

Y(4S) transitions (above open beauty threshold) much more
difficult [high backgrounds]  only recent results
Y(4S)  Y(nS)
Phys.Rev.D75:071103,2007
Y(4S)Y(1S)
As predicted by simplest PCAC
matrix elements
PRL 96,232001(2006)
Y(4S)Y(2S)
Low mass structure to be
understood!!
Y(3S)  Y(nS)



arXiv:0706.2317
From CLEO’s run @ Y(3S) [5x106
Y(3S)]
Fit to the Multipole Expansion
Breaking of the expansion
parameters
Results consistent with no ‘C’ term
The Multipole Expansion model fits the data
(but not in its ‘naivest’ form)
Y(2S)Y(1S)

0
h,
Rates predicted by QCD ME
BF(Y(2S)hY(1S))=(8.1±0.6)10-4

[Kuang hep-ph/0601044]
Direct search from CLEO 
5s evidence
Egg-mgg (MeV)
BF(Y(2S)hY(1S)) = (2.5±0.7±0.5)10-4
BF(Y(2S)0Y(1S)) < 2.1 10-4
Quarkonium polarizations
QCD predicts high pT S-wave quarkonium to be
transversely polarized in pp collisions.
 Recent updates on J&y(2S) (CDF) and Y(nS) (D0):
s T  2s L
s T  2s L
arXiv:0704.0638
J/y
s T  2s L
s T  2s L
NRQCD
CDF Y(1S)
PRL88,161802 (2002)
800 pb-1
Clear violation of NRQCD for J/y, y(2S), Y(1S) [Y(2S) follows NRQCD]
BhcK*,hc




(*)
K
Very little known about dynamics
involving hc.
NRQCD predicts
Br(BccJK(*))~Br(BhcK(*))~10-4
recent measurements:
Br(B0hcK*0)=(6.1±0.8±1.1)10-4
Br(B+hcK+)x Br(hchcg) <5.2 10-5
Br(B0hcK*0) x Br(hchcg) <2.4 10-4
Suppression in hc production
[or low Br(hc hcg)]
arxiv:0707.2843
The new zoology
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X(3872)
The 1-- family Y(4260)
The 3940 family X(3940)
breaking news
X(3872): known facts

Decays

XJ/y  (original observation)

Maybe J/y r
BF(XJ/y w)~ BF(XJ/y r)
 XJ/y g
B(X  J/y g )
 0.19  0.07
Implications:
B(X  J/y    )



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C(X)=+1
Belle+BaBar
C( in J/y  decay)=-1
I()=L()=1  consistent with J/yr decay hyp.
Production


only B decays so far
No prompt e+e- production observed (BaBar
arXiv:0707.1633)
Analysis of JPC of X(3872)
PRL 98:132002 (2007)
Full angular analysis of XJ/y decays
Only compatible options:
JPC=1++ or 2-+
(and with J()=1)
Belle (hep-ex/0505038)
disfavours P=-  JPC=1++
1++
2-+
1-0++
The X(3872) puzzle
y(4160)
Increasing L 
y(4040)
hc
Above DD threshold (allowed):
should have large width but it is
narrow
J
X(3872)?
Open charm thr.
h’c y’ c
c2
(2S+1)L
cc1
Increasing n 
M(MeV)
Not matching any predicted state!
y(3770)
hc
cc0
J/y
Charmonium highly suppressed
decay into J/y r (isospin violation)

(pot. Models)
Open options
DD* molecule


JPC

Tetraquark

More from theorists…
Right above the threshold
favours DD* decay over
J/y over J/yg (as
observed)

Explains small width
Predicts a set of 4 states (2
charged and 2 neutral).

Finding the charged state is
critical
X(3872)D0D*0


Belle [PRL 97, 162002 (2006)] observed X(3872)D0D00
Confirmation and integration from BaBar in BDD*K
B+ & B0  D0D*0K
Mass and BR measurement
M  (3875.2 11..31  0.5) MeV


Br ( B  XK ; X  DD *)
 (1.7  0.4  0.6)105
BABAR-PUB-07/049
Hints of X in neutral B decays
M  (0.7  1.9) MeV
Warning!
Br ( B 0  XK 0 ; X  DD*)
very low significance
 (2.2  1.0  0.5)105


5
N.B. Br ( B  XK ; X  J /y)  (1.14  0.20)10 [ PDG '06]
X(3872): G and angular analysis
c2
1-
JP=1+
2-
2+
cos(Helicity angle)
First info on G (≠0 @ 1.3 s)
G  (3.642..63  0.9) MeV
BABAR-PUB-07/049
First angular analysis (still low stat)
X(3872): update on J/y
Belle-CONF-0711
Update mass and BF in BXK, XJ/y 
B±XK±
B0XKS
M  (0.22  0.90  0.27) MeV
Consistent with:
no mass difference Br ( B   XK  ; X  J /y)
no rate difference Br ( B 0  XK ; X  J /y)  0.94  0.24  0.10
S
Prior results: BaBar PRD73, 011101 (2006)
6.5s
(first obs.)
X(3872) mass
Poor agreement
among mass
measurements:
XJ/y and
XDD(*) differ by
~4s
Neutral and charged
B mesons in
XJ/y by 1.5s
Predicted by tetraquark model
(but why so close to threshold?)
[my extrapolation]
J/y average
DD average
TWO STATES? X(3872) & X(3876) ?
The new zoology


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X(3872)
The 1-- family
The 3940 family
breaking news
The 1-- family
Several resonances observed in e+e-  YgISR
(certainly JPC=1--)
Y(4260)J/y
Confirmation + J/y00:
CLEO PRD74, 091104 (2006)
CLEO-c PRL 96, 162003 (2006)
A new state: Y(4260)
PRL 95, 142001 (2005)
Yet another state Y(4350)
PRL 98, 212001 (2007)
Y(4350)y(2S)
The youngest of the 1-- family
arXiv:0707.3699
arXiv:0707.2541
M  4008  4072
28 MeV
Confirmation
of BaBar
M  4361  9  9MeV
Γ  74  15  15MeV
Γ  226  4487
79 MeV
Γ  48  15  3 MeV
5.8s
NEW
M  4247  1217
26 MeV
NEW
8
Γ  108  1910
MeV
Zoomed
BaBar
YJ/y
M  4664  11  5 MeV
Yy(2S)
Y(4008)
Y(4260)
High mass region
DECAY PROPERTIES
Decay properties
Y(4350)
Y(4660)
f0 dominating?
Threshold effects?
hep-ex/0607083
DD
[Belle: arXiv:07080082]
D(*)D(*) in ISR
Most of these 1-- states should preferentially
decay into D(*)D(*) states. Can we see
them?
PRL 98, 092001 (2007)
 Basically all R scan other than
non-resonant continuum understood
DD*
arXiv:07080082
DDπ,
not D(2010,2007)
continuum
Xsection (pb)
D *D *
y(3770), y(4040), y(4415)
[regular charmonia]
clearly visible, nothing else
S [D(*)D(*)()]
J/y KK in ISR



Knowledge of the strangeness content of these resonances is critical
to disentangle their nature
CLEO-c already showed few e+e-  Y(4260)J/y K+KBelle (ISR): first observation of e+e-  J/y K+K- and J/y KsKs
e+e-  J/y K+K-
e+e-  J/y KSKS
CLEO-c
@4260
s(e+e- J/yKsKs)/ s(e+e- J/yK+K-)=0.6+0.5-0.4
Consistent with isospin (0.5)
BELLE-CONF-0772
1-- family: recap
Only seen in
y(2S)
4660
4350
4260
4008
M(MeV)
(2S+1)L
4 Ys to place !
J

y(4160)
y(4040)
y’
Open charm thr.

y(3770)
“new physics”?
J/y
Why not the
ordinary
Y(4040)?
(pot. Models)
1--
Not matching
any potential
model
prediction
Too narrow
1--
JPC
4260 can be fit by a
tetraquark model
(decaying into J/yf0 …) or
a hybrid (with g)
The new zoology




X(3872)
The 1-- family
The 3940 family
breaking news
The 3940 family
JPC (?)
1++,…
3943±17 87±34
Z ggZ (ZDD)
2++
3929±5
PRL 98, 082001 (2007)
(MeV)
0-+,1++ 3943±8
PRL 94, 182002 (2005)
YJ/yw
XDD*
M
G (MeV)
Observed in
X e+e-J/yX (XDD*)
Y BYK (YJ/yw)
<39
29±10
PRL 96, 082003 (2006)
ZDD
G. Cibinetto, talk at this conference
Confirmation of Y(3940) (BKwJ/y)
+-0
BYK
New result, based on 350 fb-1:
Belle’s evidence for BYK, YJ/yw confirmed
preliminary
B0YKS
~30MeV lower mass than Belle’s
 Narrower width
 Clear demonstration of decay into w
Preliminary BF estimate similar to Belle’s (~10-5)
Y(3940) closer to X(3940)
Can they be the same state?
Isospin
cons.
B0/B
M(J/y w) (GeV)
“Just” charmonium states?
J
M(MeV)
(2S+1)L

X,Y
X

Z
Open charm thr.
h’c
hc
cc0 c
c1
Poor match with
predictions

y(3770)
cc2
(pot. Models)
If X≠Y, difficult to
explain absence
of Yopen
charm

JPC
Above threshold?
Hybrid?
The new zoology




X(3872)
The 1-- family
The 3940 family
breaking news!!
Obtain J/yD(*)D(*)
samples through
kinematic separation,
look at m(D(*)D(*))
after background
subtraction:
X(4160) D*D*
e+ e-  J/y D(*)D(*)
reconstructed
3.8 s
Number of events
J/y D+
D*
BELLE-CONF-0705
Inferred
(Recoil mass)
M = 3942 ±6 MeV
Gtot =37 ±12 MeV
Nev= 52 ±11
D*D*
D
M(DD)
M(DD*)
5.5 s
J/y D*+
D*
D
M(D*D*)
M = 4156 +25
- 20
+111
Gtot = 37 - 61
Nev= 24 +12
- 8
±15MeV
±21MeV
M(D*D)
One more particle to explain …
JCP=0-+ not excluded (hc(3S))
The first charged state: Z(4430)!
B±Z±Ks or B0ZK±
Z±y(2S)±
BELLE-CONF-0773
Total significance: 7.3s
M = (4433±4) MeV
G= (44+17-13) MeV
Too narrow to
be a reflection
BF(BKZ)xBF(Zy(2S))=(4.1±1.0±1.3) 10-5
Xcheck: separate in
subsamples
Prior search with no evidence:
BX+K with X+J/y 0
BF and mass consistent
between B± and B0 within
large errors [in B± decays
M=(4430±9) MeV ;
BF±/BF0=1.0±0.4 ]
PRD 71, 031501 (2005)
Updated properties
M(MeV)
The 1-- family:
Charmonia,
tetraquarks,
molecules,
(2S+1)L
J
hybrids?!?
X(3872)
the best
tetraquark
candidate
Yet
another
particle:
X(4160)
[hc(3S)?]
Summary
Z(4430): the first
charged state
y(4415)
y(4160)
X,Y
y(4040)
X
Z
h’c y’ c
c2
hc
J/y
News on the 3940 family
Open charm thr.
cc1
cc0
y(3770)
hc
(pot. Models)
JPC
+ updates on Y(nS)Y(mS) transitions
Thresholds and new states
Molecular models
and threshold
effects require
vicinity to
threshold
Y(4660)

Z(4430)

Y(4350)
Y(4260)
X(4160)
Is this the case?
XYZ(3940)
X(3872)

The observation matrix
J/y
D(*)D(*)
J/yw
J/y0
y(2S)
J/yK,
Y(2S)
Mass
range
for B
Low
stat
No ISR
study
Mass
range!
No ISR
No ISR
No 0
No
Search
No B-dec Mass
window
X(3872) Seen
Seen
Not
seen
Not
seen
Not
seen
No
search
N/A
Seen
Y(3940) No
search
X(3940) Seen
?
No
search
Not
seen
No
search
No
search
No fit
Y(4260) Seen
No fit
No fit
No
search
No
search
No
search
Not seen N/A
Y(4350) Not
seen
No fit
No fit
No
search
No
search
No
search
Seen
N/A
Z(4430) No
search
No
search
No fit
No
search
Seen
No
search
No
search
No
search
Y(4660) Not
seen
No fit
No fit
No
search
No
search
No
search
Seen
N/A
Notes
J/yg
Comments & Perspectives

No systematic search on present B-Factory data



Data involving D mesons have low stat (e.g.
Br(Y(4260)DD)/Br(Y(4260)->J/y)<6.7 @95% C.L.
– BaBar prelim)


Groups working on this shrinking, should be revitalized
Also Tevatron has some homework (e.g. bottomonium
spectroscopy)
100 times the stat would help  SuperB or intermediate?
Hadron colliders have limited power:


cannot do all the needed final states
Limited capability at measuring JCP
Updated properties
The 1-- family:
The discovery and
Charmonia,
tetraquarks,
identification of a new
molecules,
(2S+1)L
J spectroscopy seems close
hybrids?!?
M(MeV)
Summary
X(3872)
the best
tetraquark
candidate
(?)
Yet
another
particle:
X(4160)
[hc(3S)?]
y(4415)
y(4160)
X,Y
y(4040)
X
Z
h’c y’ c
c2
hc
J/y
News on the 3940 family
Open charm thr.
cc1
cc0
Z(4430): the first
charged state
y(3770)
hc
(pot. Models)
JPC
+ updates on Y(nS)Y(mS) transitions
bakup
Fits to J/y KK invariant mass
‘Standard ‘ y(4415) + 1 BW:
M = (4875±132) MeV
G = (630±126) MeV
single BW:
M = (4430±38) MeV
G = (254±49) MeV
CLEO and Belle on 4260
Search for X(3872)J/y g in
386fb
continuum
-1
arXiv:0707.1633
J/y production observed in continuum
while no evidence of cc states.
cc1,2 or
X(3872)
X>2 ch
cc production is consistent with
the expected contributions
from prompt y(2S) production
feed-down to cc: no evidence
of prompt cc1,2
No evidence of X(3872)
production in e+e- annihilation.
cc1
X(3872)
cc2
Below open charm threshold