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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:

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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 HDD**

  • 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-


The new zoology

X(3872)

The 1-- family

The charged states

hot off the press


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)

    • Full angular analysis from CDF

    • 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 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 XJ/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:0809.1224

Is 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 BDD*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:

XJ/ypp and XDD(*) differ by ~3.5s

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

Predicted by tetraquark model

(but why so close to threshold?)


The new zoology

X(3872)

The 1-- family

The charged states

hot off the press


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

Yy(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 gpp)

J/y

(pot. Models)

JPC

1--

1--


The new zoology

X(3872)

The 1-- family

The charged states

hot off the press


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 Byp±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:0811.0564

BaBar 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:0905.2869

Belle 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.


PRD 78, 072004 (2008)

Z1 and Z2cc1p

Same analysis strategy

b+d


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 new zoology

X(3872)

The 1-- family

The charged states

hot off the press!!


The 3940 family

PRL 94, 182002 (2005)

PRL 96, 082003 (2006)

PRL 101, 082001 (2008)

PRL 98, 082001 (2007)

ZDD

YJ/yw

XDD*


New Belle peak in ggwJ/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 BYK YJ/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- - family

Summary

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


backup


G. Cibinetto, talk at this conference

Confirmation of Y(3940) (BKwJ/y)

p+p-p0

BYK

preliminary

  • New result, based on 350 fb-1:

  • Belle’s evidence for BYK, YJ/ confirmed

  • ~30MeV lower mass than Belle’s

  • Narrower width

  • Clear demonstration of decay into w

  • Preliminary BF estimate similar to Belle’s (~10-5)

B0YKS

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 Yopen 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


Thresholds and new states

Y(4660)

Y(4350)

Y(4260)

X(4160)

XYZ(3940)

X(3872)


CLEO and Belle on 4260


Search for X(3872)J/yg 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 results

Experiments

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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