Heavy Quarkonium Spectroscopy

1
Heavy Quarkonium Spectroscopy

• Riccardo Faccini
• University La Sapienza and INFN Rome
• Roma, 2 ottobre 2007
• tratto dal talk ad LP07

2
Quarkonium for Pedestrians
Only charmonium and bottomonium considered here

• Quarkonium is a bound state of a quark and an
  antiquark
• Relevant quantum numbers n,L,S,J
• Relationship with Parity and Charge Conj
• P(-1)L1, C(-1)LS
• Not all JPC allowed (e.g. 0-,0--,1-,2-
  forbidden)
• Decay Properties
• 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

3
Charmonium state of the art
same JPC as J/y but mostly D wave !
(2S1)LJ
y(4160)
Increasing L ?
M(MeV)
y(4040)
Open charm thr.
y(3770)
Increasing n ?
hc
y
cc2
hc
cc1
cc0
Recent acquisitions
J/y
hc
(pot. Models) QWG hep-ph/0412158
JPC
Basically all states below the open charm
threshold are observed and explained
4
Bottomonium state of the art
hb (x3) completely missing
2 hb and 3 D wave states are narrow but not
observed
Open bottom thr.
Increasing L ?
Y(3S)
c(2P)b2,1,0
Y(1D)
Increasing n ?
Y(2S)
c(1P)b2,1,0
Unconfirmed J assignments of all the cb s
Y(1S)
(pot. Models) QWG hep-ph/0412158
8 narrow resonances still missing !
5
Beyond the quarkonium

• Search for states with 2 quarkssomething else
• New forms of aggregation
• Expected but never identified!!!
• Hybrids qqn gluons
• Lowest state 1- (forbidden for quarkonium)
• Dominant decay H?DD
• Tetraquarks qqqq
• Large amount of states
• small widths also above threshold
• Molecules MqqMqq
• Smaller number of states but still small widths
  also above threshold

• Search for resonances
• with non-quarkonium JPC
• unnaturally small widths
• not null charge would be clear indication of
  something new going on

6
Measuring the quantum numbers
gISR
e
X

• Production
• ISR only produces with same quantum numbers as
  the photon (JPC1--)
• gg only produces with C
• Double charmonium production
• ee- ? g?Xcc1Xcc2
• Possible only if quantum numbers of the two
• charmonia can be combined to give a 1--.
• Decay
• Angular distributions of decay products depend on
  JP.
• Selection rules
• Conservation of J
• Conservation of P,C in strong and e.m. decays

e-
e
e
X
e-
e-
7
Experiments
Samples used in results
58MJ/y, 14M y(2S)

• ee- ?Charmonium (CLEO-c, BES-II)
• L1033/cm2/s
• E3.0-4.3 GeV
• ee- ? Y(4S) (BaBar, Belle, CLEO)
• L1034/cm2/s
• Charmonium in B decays, ISR and gg production
• Capability to measure JPC also in production
• pp colliders (CDF, D0)
• High Xsection ? copious production
• Extremely high backgrounds

3M y(2S), 1.8 M y(3770)
1.5M Y(1S),1.9M Y(2S), 1.7M Y(3S),9M Y(4S)
657M Y(4S)
383M Y(4S)
1.3 fb-1
800pb-1

• Disclamers
• time is very short
• ? could not cover everything
• theory statements are indicative

8
Quarkonium Spectroscopy
9
Updates on 1-- charmonium states
NEW
arXiv0705.4500
Belle-CONF-0771
NEW
14s
improved measurements, including interference for
the first time!!!
MeV y(3770) y(4040) y(4160) y(4415)
M 37712 40395 41926 44158
G 257 8114 7315 7321
First exclusive decay observed DD2(2460)
dominant ? 3D1 candidate

• CLEO-c observes y(3770)?cc0g
• Confirms 3D assignment hep-ex/0605070

10
Y(nS)?Y(mS) transitions

• The issue
• Quarkonium transitions between 3S1 states
  described by the QCD Multipole Expansion
• Tests heavy quark and low energy hadronic systems
• BR(X(nS)?X(mS)h)/ BR(X(nS)?X(mS)pp)
• pp invariant mass spectra ? simplest PCAC matrix
  element expects enhancement at high masses
• Data on Charmonium transitions well fitted by
  predictions
• 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

11
Y(4S) ? Y(nS)pp
PRL 96,232001(2006)
Phys.Rev.D75071103,2007
Y(4S)?Y(1S)pp
Y(4S)?Y(2S)pp
As predicted by simplest PCAC matrix elements
Low mass structure to be understood!!
12
Y(3S) ? Y(nS)pp
NEW

• From CLEOs run _at_ Y(3S) 5x106 Y(3S)
• Fit to the Multipole Expansion parameters
• Results consistent with no C term

Breaking of the expansion
The Multipole Expansion model fits the data (but
not in its naivest form)
arXiv0706.2317
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Y(2S)?Y(1S) h,p0

• Rates predicted by QCD ME
• BF(Y(2S)?hY(1S))(8.10.6)10-4
• Kuang hep-ph/0601044
• Direct search from CLEO ? 5s evidence

Egg-mgg (MeV)
BF(Y(2S)?hY(1S)) (2.50.70.5)10-4 BF(Y(2S)?p0Y(
1S)) lt 2.1 10-4
14
Quarkonium polarizations

• QCD predicts high pT S-wave quarkonium to be
  transversely polarized in pp collisions.
• Recent updates on Jy(2S) (CDF) and Y(nS) (D0)

arXiv0704.0638
Y(1S)
NRQCD
CDF PRL88,161802 (2002)
J/y
800 pb-1
Clear violation of NRQCD for J/y, y(2S), Y(1S)
Y(2S) follows NRQCD
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B?hcK,hc K()
NEW

• Very little known about dynamics involving hc.
• NRQCD predicts Br(B?ccJK())Br(B?hcK())10-4
• recent measurements
• Br(B0?hcK0)(6.10.81.1)10-4
• Br(B?hcK)x Br(hc?hcg) lt5.2 10-5
• Br(B0?hcK0) x Br(hc?hcg) lt2.4 10-4
• Suppression in hc production
• or low Br(hc ?hcg)

arxiv0707.2843
16
The new zoology

• X(3872)
• The 1-- family Y(4260)
• The 3940 family X(3940)
• breaking news

17
X(3872) known facts

• Decays
• X?J/y pp (original observation)
• Maybe J/y r
• BF(X?J/y w) BF(X?J/y r)
• X?J/y g
• Implications
• C(X)1
• C(pp in J/y pp decay)-1
• I(pp)L(pp)1 ? consistent with J/yr decay hyp.
• Production
• only B decays so far
• No prompt ee- production observed (BaBar
  arXiv0707.1633)

BelleBaBar
NEW
18
Analysis of JPC of X(3872)
PRL 98132002 (2007)

• Full angular analysis of X?J/ypp decays

Only compatible options JPC1 or 2- (and
with J(pp)1)
1
2-
Belle (hep-ex/0505038) disfavours P- ? JPC1
1--
0
19
The X(3872) puzzle
Not matching any predicted state! Above DD
threshold (allowed) should have large width but
it is narrow Charmonium highly suppressed decay
into J/y r (isospin violation)
(2S1)LJ
y(4160)
Increasing L ?
M(MeV)
y(4040)
X(3872)?
Open charm thr.
y(3770)
Increasing n ?
hc
y
cc2
hc
cc1

• Open options
• DD molecule
• Right above the threshold
• favours DD decay over J/ypp over J/yg (as
  observed)
• Tetraquark
• Explains small width
• Predicts a set of 4 states (2 charged and 2
  neutral).
• Finding the charged state is critical

cc0
J/y
(pot. Models)
hc
JPC
More from theorists
20
X(3872)?D0D0
NEW

• Belle PRL 97, 162002 (2006) observed
  X(3872)?D0D0p0
• Confirmation and integration from BaBar in B?DDK

BABAR-PUB-07/049
B B0 ? D0D0K
Hints of X in neutral B decays
Mass and BR measurement
Warning! very low significance
N.B.
21
X(3872) G and angular analysis
Dc2
1-
JP1
2-
2
cos(Helicity angle)
First angular analysis (still low stat)
First info on G (?0 _at_ 1.3 s)
NEW
BABAR-PUB-07/049
22
X(3872) update on J/ypp
NEW
Belle-CONF-0711

• Update mass and BF in B?XK, X?J/y pp

6.5s (first obs.)
B0?XKS
B?XK
Consistent with no mass difference no rate
difference
Prior results BaBar PRD73, 011101 (2006)
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X(3872) mass
NEW

• Poor agreement among mass measurements
• X?J/ypp and X?DD() differ by 4s
• Neutral and charged B mesons in X?J/ypp by 1.5s

my extrapolation
NEW
DD average
J/ypp average
Predicted by tetraquark model (but why so close
to threshold?)
TWO STATES? X(3872) X(3876) ?
24
The new zoology

• X(3872)
• The 1-- family
• The 3940 family
• breaking news

25
The 1-- family

• Several resonances observed in ee- ? YgISR
  (certainly JPC1--)

Y(4260)?J/ypp
Confirmation J/yp0p0 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)pp
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The youngest of the 1-- family
arXiv0707.3699
arXiv0707.2541
Confirmation of BaBar
5.8s
NEW
NEW
NEW
Zoomed BaBar
Y?y(2S)pp
Y?J/ypp
27
Decay properties
Y(4008)
Y(4260)
High mass region
DECAY PROPERTIES
NEW
f0 dominating? Threshold effects?
Y(4660)
Y(4350)
28
D()D() in ISR
Belle arXiv07080082
hep-ex/0607083
DD

• Most of these 1-- states should preferentially
  decay into D()D() states. Can we see them?

y(3770), y(4040), y(4415) regular charmonia
clearly visible, nothing else
PRL 98, 092001 (2007)
DD
? Basically all R scan other than non-resonant
continuum understood
DD
Xsection (pb)
DDp,not D(2010,2007)
arXiv07080082
S D()D()(p)
continuum
29
J/y KK in ISR

• Knowledge of the strangeness content of these
  resonances is critical to disentangle their
  nature
• CLEO-c already showed few ee- ? Y(4260)?J/y KK-
  
• Belle (ISR) first observation of ee- ? J/y KK-
  and J/y KsKs

ee- ? J/y KK-
ee- ? J/y KSKS
CLEO-c _at_4260
s(ee- ?J/yKsKs)/ s(ee- ?J/yKK-)0.60.5-0.4
Consistent with isospin (0.5)
BELLE-CONF-0772
30
1-- family recap
Only seen in y(2S)pp
(2S1)LJ

• Not matching any potential model prediction
• Too narrow

4660
M(MeV)
4350
y(4160)
4260
4008
y(4040)
4 Ys to place !
Open charm thr.
y(3770)
y
new physics? 4260 can be fit by a tetraquark
model (decaying into J/yf0 ) or a hybrid (with
g?pp)
J/y
Why not the ordinary Y(4040)?
(pot. Models)
JPC
1--
1--
31
The new zoology

• X(3872)
• The 1-- family
• The 3940 family
• breaking news

32
The 3940 family
Observed in JPC (?) M (MeV) G (MeV)
X ee-?J/yX (X?DD) 0-,1 39438 lt39
Y B?YK (Y?J/yw) 1, 394317 8734
Z gg?Z (Z?DD) 2 39295 2910
PRL 98, 082001 (2007)
PRL 94, 182002 (2005)
PRL 96, 082003 (2006)
Y?J/yw
Z?DD
X?DD
33
Confirmation of Y(3940) (B?KwJ/y)
G. Cibinetto, talk at this conference
pp-p0
B??YK?
preliminary

• New result, based on 350 fb-1
• Belles evidence for B?YK, Y?J/?? confirmed
• 30MeV lower mass than Belles
• Narrower width
• Clear demonstration of decay into w
• Preliminary BF estimate similar to Belles (10-5)

B0?YKS
B0/B?
Y(3940) closer to X(3940) Can they be the same
state?
Isospincons.
M(J/y w) (GeV)
34
Just charmonium states?
(2S1)LJ

• Poor match with predictions
• Above threshold?
• If X?Y, difficult to explain absence of Y?open
  charm
• Hybrid?

M(MeV)
X,Y
X
Z
Open charm thr.
y(3770)
hc
cc0
cc1
cc2
hc
(pot. Models)
JPC
35
The new zoology

• X(3872)
• The 1-- family
• The 3940 family
• breaking news!!

36
X(4160)? DD
Obtain J/yD()D() samples through kinematic
separation, look at m(D()D())after background
subtraction
e e- ? J/y D()D()
BELLE-CONF-0705
M 3942 6 MeV ?tot 37 12 MeV Nev 52
11
reconstructed
Inferred (Recoil mass)
Somethings here, but its not X(3940)
3.8 ?
X(3940) is still there, 6.0s
D
DD
J/y D
D
Number of events
M(DD)
M(DD)
X(4160) claim new state
5.5 ?
J/y D
X(3940) Cross-check
D
D
M(DD)
M(DD)
M 4156 15MeV ?tot 37
21MeV Nev 24
25 - 20
111 - 61
One more particle to explain JCP0- not
excluded (hc(3S))
12 - 8
37
The first charged state Z(4430)!
B?ZKs or B0?Z?K Z?y(2S)p
BELLE-CONF-0773

• Total significance 7.3s
• M (44334) MeV
• (4417-13) MeV
• BF(B?KZ)xBF(Z?y(2S)p)(4.11.01.3) 10-5

Too narrow to be a reflection
Xcheck separate in subsamples BF and mass
consistent between B and B0 within large errors
in B decays M(44309) MeV BF/BF01.00.4
Prior search with no evidence B?XK with X?J/y
pp0
PRD 71, 031501 (2005)
38
Summary
Updated properties
The 1-- family Charmonia, tetraquarks,
molecules, hybrids?!?
(2S1)LJ
Z(4430) the first charged state
M(MeV)
y(4415)
y(4160)
X,Y
News on the 3940 family
X(3872) the best tetraquark candidate
y(4040)
X
Z
Open charm thr.
y(3770)
hc
y
cc2
hc
cc1
cc0
Yet another particle X(4160) hc(3S)?
J/y
(pot. Models)
hc
JPC
updates on Y(nS)?Y(mS) transitions
39
Thresholds and new states
?
Molecular models and threshold effects require
vicinity to threshold Is this the case?
Y(4660)
Z(4430)
?
Y(4350)
Y(4260)
X(4160)
XYZ(3940)
?
X(3872)
40
The observation matrix
J/ypp- D()D() J/yw J/ypp0 y(2S)p J/yK,p Y(2S)pp J/yg
Notes Mass range for B Low stat No ISR study Mass range! No ISR No ISR No p0 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
41
Comments Perspectives

• No systematic search on present B-Factory data
• Groups working on this shrinking, should be
  revitalized
• Also Tevatron has some homework (e.g. bottomonium
  spectroscopy)
• Data involving D mesons have low stat (e.g.
  Br(Y(4260)?DD)/Br(Y(4260)-gtJ/ypp)lt6.7 _at_95 C.L.
  BaBar prelim)
• 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

42
Summary
Updated properties
The 1-- family Charmonia, tetraquarks,
molecules, hybrids?!?
The discovery and identification of a new
spectroscopy seems close
(2S1)LJ
Z(4430) the first charged state
M(MeV)
y(4415)
y(4160)
X,Y
WHAT A MESS !!!! ( of data)
News on the 3940 family
X(3872) the best tetraquark candidate (?)
Rimbocchiamoci le maniche
y(4040)
X
Z
Open charm thr.
y(3770)
hc
y
cc2
hc
cc1
cc0
Yet another particle X(4160) hc(3S)?
J/y
(pot. Models)
hc
JPC
updates on Y(nS)?Y(mS) transitions
43
bakup
44
Fits to J/y KK invariant mass
Standard y(4415) 1 BW M (4875132) MeV G
(630126) MeV
single BW M (443038) MeV G (25449) MeV
45
CLEO and Belle on 4260
46
Search for X(3872)?J/y?g in continuum
386fb-1
arXiv0707.1633
J/? production observed in continuum while no
evidence of ?c states.
cc1
X(3872)
?c1,2 or X(3872)
cc2
Xgt2 ch
?c production is consistent with the expected
contributions from prompt y(2S) production
feed-down to cc no evidence of prompt ?c1,2 No
evidence of X(3872) production in ee-
annihilation.
47
Below open charm threshold