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### Exotic states with cc

Riccardo Faccini

University “La Sapienza” and INFN Rome

FPCP 2009

31 May 2009

Lake Placid, NY, USA

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:
- P=(-1)L+1, C=(-1)L+S
- 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

Charmonium: state of the art

same JPC as J/y but mostly D wave !

(2S+1)LJ

y(4160)

Increasing L

M(MeV)

y(4040)

Open charm thr.

y(3770)

y’

Increasing n

h’c

cc2

hc

cc1

cc0

J/y

hc

(pot. Models)

QWG: hep-ph/0412158

JPC

Basically all states below the open charm threshold are observed and explained

Beyond the quarkonium

- Search for states with 2 quarks+”something else”
- New forms of aggregation
- Expected but never identified!!!
- Hybrids: qq+n gluons
- Lowest state 1-+ (forbidden for quarkonium)
- Dominant decay HDD**
- Tetraquarks: [qq’][qq’]
- Large amount of states
- small widths also above threshold
- Molecules: M[qq]M[q’q’]
- 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

Measuring the quantum numbers

gISR

e+

X

- Production:
- ISR only produces with same quantum numbers as the photon (JPC=1--)
- gg only produces with C=+
- Double charmonium production

e+e- 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 electromagnetic decays

e-

e+

e+

X

e-

e-

X(3872): known facts

- Decays
- XJ/y pp (original observation)
- Maybe J/y r
- BF(XJ/y w)~ BF(XJ/y r)
- Full angular analysis from CDF
- XJ/y g

Implications:

- C(X)=+1
- C(pp in J/y pp decay)=-1
- I(pp)=L(pp)=1 consistent with J/yr decay hypothesis
- JPC=1++ or 2-+ from angular analysis
- Production
- only B decays so far
- No prompt e+e- production observed (BaBar arXiv:0707.1633)

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)

y(4160)

(2S+1)LJ

Increasing L

M(MeV)

Open options

- DD* molecule
- Right above the threshold
- favors 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 these states is critical

y(4040)

X(3872)?

Open charm thr.

y(3770)

Increasing n

h’c

y’

cc2

hc

cc1

cc0

J/y

(pot. Models)

hc

JPC

Are there two XJ/ypp ?

arXiv:0807.3699

- CDF with largest sample investigates the mass distribution for two resonances closeby

Fitted mass difference as a function of first gaussian fraction

DM<3.2 MeV @90%C.L.

arXiv:0809.1224Is the X in B0 and B+ decays the same?

B± XK±

B0 XKS

X J/ypp

More in

Phys.Rev.D77:111101,2008

Consistent with one state, equally present in decays

X(3872)D0D*0

- Belle [PRL 97, 162002 (2006)] observed X(3872)D0D0p0
- Confirmation and integration from BaBar in BDD*K[PRD 77, 011102(2008)]
- Most recent result from Belle

D*D0p0

D*D0g

arXiv:0810.0358

X(3872) mass

[my extrapolation]

Poor agreement among mass measurements:

XJ/ypp and XDD(*) differ by ~3.5s

TWO STATES? X(3872) & X(3876) ?

Predicted by tetraquark model

(but why so close to threshold?)

The 1-- family

Several resonances observed in e+e- YgISR(certainly JPC=1--)

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

The youngest of the 1-- family

PRL99, 142002 (2007)

5.8s

Present in low stat in BaBar’s publication

Zoomed

BaBar

Yy(2S)pp

Y(4260)

PRL99, 142002 (2007)

arXiv 0808.1543

DECAY PROPERTIES

f0 dominating?

Threshold effects?

Y(4660)

Y(4350)

PRL101,172001 (2008)X(4630) [or Y(4660)?]LcLc

- Y(4660) good candidate for a LcLc bound state
- Search for ISR e+e- LcLcg events

Right sign p

CFR

Wrong sign p

In the discovery mode

Assuming same state as y(2S)pp

!

ψ(3770)

ψ(3770)

DD

DD

ψ(4415)

ψ(4415)

ψ(4040)

ψ(4040)

ψ(4160)

ψ(4160)

G(3942)

G(3942)

ψ(4260)

ψ(4260)

D*D

D*D

D*D*

D*D*

ISR search for Y(4260)→ D(*)D(*)Y(4260) is 1-- charmonium state should decay predominantlyto DD, D*D, and D*D*

BABAR: PRD 79, 092001 (2009), 384

1-- family: recap

Only seen in y(2S)pp

(2S+1)LJ

- Not matching any potential model prediction
- Too narrow

4660

M(MeV)

4350

y(4160)

4260

y(4040)

Open charm thr.

y(3770)

y’

“new physics”?

4260 can be fit by a tetraquark model (decaying into J/yf0 …) or a hybrid (with gpp)

J/y

(pot. Models)

JPC

1--

1--

The Z(4430)+

- Charged states a strong prediction of the tetra-quark model
- First observed by Belle in PRL100, 142001 (2008)
- Search for Z±

J/y or y(2S) + p±

In Byp±K decays

M=4433±4±2 MeV

G=45+18-13+30-13 MeV

121±30 evts , 6.5 s

Criticisms to “discovery analysis”

- Only “global”

efficiency

correction

- Poor

treatment of 3-body decays (cut away dominant resonances – no interference/reflections)

- Arbitrary choice of background shape

VETOES

arXiv:0811.0564BaBar Analysis

- Event-by-event efficiency correction
- Describe the Kp system in detail
- Mass
- Angular distributions fitted with Legendre Polynomials

Comparison of BaBar background with data

Same “veto” definition as Belle

BaBar results

- Fitting without vetoes

m=4476±8 MeV/c2; Γ=32±16 MeV; signal size: 2.7σ

[offset of 43±9 MeV w.r.t. Belle]

- Same vetoes as Belle

m=4439±8 MeV/c2; Γ=41±33 MeV; signal size 1.9σ

- Conclusions:
- mistreatement of background might enhance significance
- veto might bias signal mass measurement

arXiv:0905.2869Belle Dalitz Plot Analysis

- Belle’s observation confirmed, but errors increase
- Including y(2S)W

W=

- m=4443+24-18 MeV
- Γ=109+113-71 MeV

CFR. BaBar excludes 3.1 10-5 @90%C.L.

Summary of charged states

The 1– family

(2S+1)LJ

M(MeV)

Z(4430)

y(4415)

y(4160)

Z(4250)

Z(4050)

y(4040)

Open charm thr.

y(3770)

h’c

y’

cc2

hc

cc1

cc0

J/y

(pot. Models)

hc

JPC

The 3940 family

PRL 94, 182002 (2005)

PRL 96, 082003 (2006)

PRL 101, 082001 (2008)

PRL 98, 082001 (2007)

ZDD

YJ/yw

XDD*

New Belle peak in ggwJ/y

M: 3914 3 2 MeV,

G: 23 10 +2-8 MeV,

Nres = 55 14 +2-14 events

Signif. = 7.7s

Preliminary

The 4 states near 3940

Mass(GeV)

Range: (s(stat.)+s(sys.))

Y(3940)

Belle

X(3940)

Better analysis of the J/y w mass spectrum needed!!

Z(3930)

Good overlap with

BaBar “Y(3940)” values

Would allow only the 0++ assignment

This X(3915)

Width(GeV)

Y(4140) from CDF

Search for BYK YJ/yf

arXiv:0903.2229

14 5events

M=m(+-K+K-)-m(+-)

M: 4143.0 2.9 1.2 MeV,

G: 11.7 +8.3-5± 3.7MeV,

Signif. > 3.8s

Lowest lying hybrid, expected at m~4200MeV

Possible JPC=0++,1-+,2++

Another ‘edge’ state, better candidate molecule

More on the 1- - familySummary

The charged candidates

(2S+1)LJ

M(MeV)

Z(4430)

y(4140)

y(4415)

y(4160)

Z(4250)

Z(4050)

X(3872) never ending story

y(4040)

X

Z

Y

Open charm thr.

y(3770)

One more member of

the 3940 family

h’c

y’

cc2

hc

cc1

cc0

J/y

(pot. Models)

hc

X(4160)

New state from CDF

Good Hybrid candidate

JPC

Outlook

Plenty of states seen with low stat and in only one channel next generation [SuperB(elle)?] needed

G. Cibinetto, talk at this conferenceConfirmation of Y(3940) (BKwJ/y)

p+p-p0

BYK

preliminary

- New result, based on 350 fb-1:
- Belle’s evidence for BYK, YJ/ confirmed
- ~30MeV lower mass than Belle’s
- Narrower width
- Clear demonstration of decay into w
- Preliminary BF estimate similar to Belle’s (~10-5)

B0YKS

B0/B

Y(3940) closer to X(3940)

Can they be the same state?

Isospincons.

M(J/y w) (GeV)

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(*)

BELLE-CONF-0705

M = 3942 ±6 MeV

tot =37 ±12 MeV

Nev= 52 ±11

reconstructed

Inferred (Recoil mass)

Something’s here, but it’s not X(3940)

3.8

X(3940)

is still there, 6.0s

J/y D+

D*

D*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(D*D)

M(D*D*)

M = 4156 ±15MeV

tot = 37 ±21MeV

Nev= 24

+25

- 20

+111

- 61

One more particle to explain …

JCP=0-+ not excluded (hc(3S))

+12

- 8

“Just” charmonium states?

(2S+1)LJ

- Poor match with predictions
- Above threshold?
- If X≠Y, difficult to explain absence of Yopen charm
- Hybrid?

M(MeV)

Z

Y=X(3915)

X

Open charm thr.

y(3770)

h’c

cc0

cc1

cc2

hc

(pot. Models)

JPC

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

Search for X(3872)J/yg in continuum

386fb-1

arXiv:0707.1633

J/ production observed in continuum while no evidence of c states.

cc1

X(3872)

c1,2 or X(3872)

cc2

X>2 ch

c production is consistent with the expected contributions from prompty(2S) production feed-down tocc: no evidence of prompt c1,2

No evidence of X(3872) production in e+e- annihilation.

Samples used in resultsExperiments

58MJ/y, 14M y(2S)

- e+e-Charmonium (CLEO-c, BES-II)
- L~1033/cm2/s
- E=3.0-4.3 GeV
- e+e- Y(4S): (BaBar, Belle, CLEO)
- L~1034/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

2.4bf-1

- Disclamers:
- time is very short
- could not cover everything
- theory statements are indicative

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