Theoretical Progress on Theoretical Progress on XYZ StatesXYZ States

Research Center for Hadron and CSR PhysicsResearch Center for Hadron and CSR Physics

Lanzhou University & Institute of Modern Physics of CASLanzhou University & Institute of Modern Physics of CAS

Dian-Yong ChenDian-Yong Chen

Collaborated with Xiang Liu, Jun He, Shi-Lin Zhu, Xue-Qian Li, T. MatsukiCollaborated with Xiang Liu, Jun He, Shi-Lin Zhu, Xue-Qian Li, T. Matsuki

Institute of Modern Physics, CAS

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OutlineOutline

• Charmonium-like stateCharmonium-like state

Y(4260) Y(4360)Y(4260) Y(4360)

• Y(5S) hidden-bottom dipion decaysY(5S) hidden-bottom dipion decays

ZZbb(10610) Z(10610) Zbb(10650)(10650)

• SummarySummary

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Charmonium-like Charmonium-like statesstates

Y(4260) and Y(4260) and Y(4360)Y(4360) Dian-Yong Chen, Jun He and Xiang Liu Dian-Yong Chen, Jun He and Xiang Liu

PRD83, 074012 (2011)PRD83, 074012 (2011)

PRD83, 054021 (2011)PRD83, 054021 (2011)

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According to the According to the production mechanismproduction mechanism, , we can categorize these we can categorize these charmonium-like charmonium-like

statesstates X, Y, ZX, Y, Z as as four groupsfour groups::

Y(4260)

Y(4008)

Y(4360)

Y(4630)

Y(4660)

ISR processISR process

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Experimental status of Y(4260) and Experimental status of Y(4260) and Y(4360)Y(4360)

Spin-parity: J =1Spin-parity: J =1PC --

PRL95, 142001 (2005)

Y(4260)Y(4260)

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Spin-parity: J =1Spin-parity: J =1PC --

Y(4360Y(4360))

M=4324±24 MeVM=4324±24 MeV

ΓΓ==172±33 MeV172±33 MeV

PRL98, 212001 (2007) PRL99, 142002 (2007)

M=4361±9±9 MeVM=4361±9±9 MeV

ΓΓ==74±15±10 MeV74±15±10 MeV

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Theoretical explanationTheoretical explanation

• Charmonium hybridCharmonium hybrid Zhu, Kou&Pene, Close&Page

• Diquark-antidiquark stateDiquark-antidiquark state [cs][cs][cs][cs] Maiani&Riquer&Piccinini&Polosa, Ebert& Faustov & Galkin

• Molecular state ( ) Molecular state ( )

Liu&Zeng&Li, Yuan&Wang&Mo, Qiao, Ding, Torres&KhemchandaniLiu&Zeng&Li, Yuan&Wang&Mo, Qiao, Ding, Torres&Khemchandani

&Gamermann&Oset, Close&Downum&Thomas&Gamermann&Oset, Close&Downum&Thomas• Charmonium hybrid state with strong coupling with Charmonium hybrid state with strong coupling with DDDD11 and and DD DD00

Kalashnikova &Nefediev

Exotic state:Exotic state:

The lack of signal in certain channelslack of signal in certain channels also poses a serious challengea serious challenge to a number of the explanations proposed in the framework of an exotic state.explanations proposed in the framework of an exotic state.

Y(4260)Y(4260)

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• 4S-3D vector charmonium Llanes-Estrada

• 2 D1 state decay behavior Eichten, Lane, QuiggEichten, Lane, Quigg

• Mass spectrum Y(4260) ≠charmonium Segovia, Yasser, Entem, FernandezSegovia, Yasser, Entem, Fernandez

• Screened potential Y(4260) =Ψ(4S)

Li, ChaoLi, Chao

Conventional Conventional charmoniumcharmonium ：： Y(4260)Y(4260)

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• 3D charmonium or charmonium hybrid Ding, Li&Chao• The radial excited state of Y(4260) Qiao • Charmed baryonium Cotugno&Faccini&Polosa&Sabelli• The vector hybrid charmonium with strong coupling with

D*D0

Kalashnikova&Nefediev• molecular state Albuquerque & Nielsen•

Y(4360)Y(4360)

Close&Downum&ThomasClose&Downum&Thomas

Conventional + exoticConventional + exotic

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D*D*

DD*

ψ(4

040)

ψ(4

160)

Y(4

008)

ψ(4

415)

Y(4

660)

Y(4

260)

Y(4

360)

DD

DDπ

Λc+Λc

–

?

PRD77,011103(2008)

PRL100,062001(2008)

PRL98, 092001 (2007)

PRL101,172001(2008)

DD*π arXiv:0908.0231

y(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008) y

(404

0)

y(4

160)

Y(4

260)

Y(4

325) y

(441

5)

Y(4

660)

ψ(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008)

ψ(4

040)

ψ(4

160)

Y(4

260)

Y(4

360) ψ

(441

5)

Y(4

660)

R(s) = σ(e+e–→hadrons)/σ(e+e–→μ+μ–) – Ruds

y(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008) y

(404

0)

y(4

160)

Y(4

260)

Y(4

325) y

(441

5)

Y(4

660)

ψ(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008)

ψ(4

040)

ψ(4

160)

Y(4

260)

Y(4

360) ψ

(441

5)

Y(4

660)

y(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008) y

(404

0)

y(4

160)

Y(4

260)

Y(4

325) y

(441

5)

Y(4

660)

ψ(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008)

ψ(4

040)

ψ(4

160)

Y(4

260)

Y(4

360) ψ

(441

5)

Y(4

660)

R(s) = σ(e+e–→hadrons)/σ(e+e–→μ+μ–) – Ruds

The main challenge of The main challenge of YY(4260) (4260) and Y(4360) as a conventional and Y(4360) as a conventional charmonium:charmonium:No evidenceNo evidence of of YY(4260)/Y(4360) in the (4260)/Y(4360) in the obtained obtained open-charm processopen-charm process and and RR-value scan-value scan

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Non-resonant explanation for Non-resonant explanation for Y(4260) and Y(4360)Y(4260) and Y(4360)

The interference between ContinuumContinuum and ResonanceResonance

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BackgroundBackground

Y(4360) Y(4260)

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Can we reproduce the line shape of Y(4260) and Y(4360) in our model?Can we reproduce the line shape of Y(4260) and Y(4360) in our model?

Five fitting parameters: Five fitting parameters:

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Numerical results for Numerical results for Y(4260)Y(4260)

D.Y. Chen, J. He and Xiang Liu, D.Y. Chen, J. He and Xiang Liu, Phys.Rev.D83, 054021 (2011)Phys.Rev.D83, 054021 (2011)

Y(4260)

Y(4008)

M=4008±40 MeV Г=226 ±44 MeV

Belle, Phys.Rev.Lett.99:182004 (2007)

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Numerical results for Numerical results for Y(4360)Y(4360)

Dian-Yong Chen, Jun He and Dian-Yong Chen, Jun He and Xiang Liu Xiang Liu PRD83, 074012 (2011)PRD83, 074012 (2011)

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Y(5S) hidden-bottom Y(5S) hidden-bottom dipion decaysdipion decays ZZbb(10610) and (10610) and

ZZbb(10650)(10650)Dian-Yong Chen, Jun He, Xun-Qian. Li, Xiang Liu, PRD84, 074006 (2011)PRD84, 074006 (2011)

Dian-Yong Chen, Xiang Liu, Shi-Lin Zhu, PRD84, 034002 (2011)PRD84, 034002 (2011)

Dian-Yong Chen, Xiang Liu, PRD84, 094003 (2011)PRD84, 094003 (2011)

Dian-Yong Chen, Xiang Liu, PRD84, 034032 (2011)PRD84, 034032 (2011)

Dian-Yong Chen, Xiang Liu, Takayuki. Matsuki, PRD84, 074032 (2011)PRD84, 074032 (2011)

Dian-Yong Chen, Xiang Liu, Takayuki. Matsuki, preparingpreparing

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Dipion hidden-bottom decays of Y(5S)Dipion hidden-bottom decays of Y(5S)

Belle, PRL100, 112001Belle, PRL100, 112001

Y(5S)Y(1S)π+π- 0.59

Y(5S)Y(2S) π+π- 0.85

Y(5S)Y(3S) π+π- 0.52

Y(2S)Y(1S) π+π- 0.006

Y(3S)Y(1S) π+π- 0.0009

Y(4S)Y(1S) π+π- 0.0019

Decay channel MeVDecay channel MeV

101022

Belle, PRD82, 091106(R) (2010)Belle, PRD82, 091106(R) (2010)

PuzzlePuzzle existing in existing in Y(5S)Y(5S) dipion hidden-bottom dipion hidden-bottom

decaysdecays

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Explanations of anomalous branching ratios of Y(5S) Explanations of anomalous branching ratios of Y(5S) hidden-bottom dipion decayshidden-bottom dipion decays

• RescatteringRescattering mechanism mechanismC. Meng, K.T. ChaoC. Meng, K.T. Chao PRD77, 074003 (2008) PRD77, 074003 (2008) PRD78, 034022 (2008)PRD78, 034022 (2008) PRD78, 074001 (2008)PRD78, 074001 (2008)Yu. A. Simonov Yu. A. Simonov JETP Lett. 87, 147 (2008) JETP Lett. 87, 147 (2008)H.W. Ke, Xiang Liu, X.Q. LiH.W. Ke, Xiang Liu, X.Q. Li PRD82, 054030 (2010) PRD82, 054030 (2010)

• Bottom analogueBottom analogue ofof Y(4260) Y(4260)s.s. Godfrey, S.L. Olsen Godfrey, S.L. Olsen arXiv:0801.3867arXiv:0801.3867

• ExoticExotic structure-structure-TetraquarkTetraquark state state near near Y(5S)Y(5S)

M. Karliner, H.J. LipkinM. Karliner, H.J. Lipkin arXiv:0802.0649arXiv:0802.0649A. Ali et al.A. Ali et al. PLB684, 28 (2010), PRL104, 162001 (2010)PLB684, 28 (2010), PRL104, 162001 (2010)

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Ali et al., PRL104, 162001Ali et al., PRL104, 162001

Tetraquark explanation to Y(10870)Tetraquark explanation to Y(10870)

Chen, He, Li,Chen, He, Li, Liu,Liu, PRD84, 074006 (2011)PRD84, 074006 (2011)

Indicate the Indicate the mistake in mistake in Ali’s workAli’s work

Propose Propose interference interference

effecteffect

New New puzzle!puzzle!

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Experiment status of two charged ZbExperiment status of two charged Zb

Belle CollaborationBelle Collaboration

arXiv:1105.4583arXiv:1105.4583

ZZbb(10610)(10610)

ZZbb(10650)(10650)

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Zb structues and new puzzleZb structues and new puzzleChen, Liu, Zhu,Chen, Liu, Zhu, PRD84, 054002 (2011)PRD84, 054002 (2011)

Two newly observed Two newly observed ZZbb structuresstructures play play important roleimportant role to to

solve “solve “new puzzlenew puzzle” in ” in Y(5S)Y(5S)Y(2S)Y(2S)ππ++ππ- - decaydecay

Question:Question: what iswhat is the source the source to generateto generate Zb(10610) Zb(10610) andand

Zb(10650)? Zb(10650)?

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• S-wave BB* and B*B* molecular statesS-wave BB* and B*B* molecular statesLiu, Xiang Liu,Deng, Zhu, EPJC56, 63 (2008) Xiang Liu, Luo, Liu, Zhu, EPJC61, 411 (2009)

Bondar, Garmash, Milstein, Mizuk, Voloshin, arXvi:1105.4473Zhang, Huang, arXiv:1105.5472 QCD sum ruleVoloshin, arXiv:1105.5829 Radiative decaysCleven, Guo, Hanhart, Meissner, EPJA, 47, 120 (2011)

Sun, He, Xiang Liu, Luo, Zhu,Sun, He, Xiang Liu, Luo, Zhu, PRD84:054002,2011PRD84:054002,2011

One-Boson-Exchange model

• Tetraquark stateTetraquark stateYang, Ping, Deng, Zong, Yang, Ping, Deng, Zong, arXiv:1105.5935arXiv:1105.5935Guo, Cao, Zhou, Chen, Guo, Cao, Zhou, Chen, arXiv:1106.2284arXiv:1106.2284

Theoretical explanation Theoretical explanation II- Exotic strucutes- Exotic strucutes

Predict BB* molecular statePredict BB* molecular state

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Theoretical explanation Theoretical explanation IIII- Mechanism- Mechanism • D. V. Bugg, D. V. Bugg, EPL96, 11002 (2011)EPL96, 11002 (2011) Cusp effect Cusp effect

• Yu. A. Simonov, Yu. A. Simonov, arXiv: 1106.1522arXiv: 1106.1522

•Dian-Yong Chen, Xiang Liu, PRD84, 094003 (2011)PRD84, 094003 (2011)

Initial single pion emission (Initial single pion emission (ISPEISPE) mechanism) mechanism

An underlying mechanism An underlying mechanism without introducing exotic without introducing exotic

explanation!explanation!

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B*B*

BB*

BB

Exp

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BB* BBB*B*

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More predictionsMore predictions

If the If the ISPE mechanismISPE mechanism is a is a universaluniversal mechanism in heavy quarkonium dipion mechanism in heavy quarkonium dipion

decays, we naturally extend the ISPE decays, we naturally extend the ISPE mechanism to study the mechanism to study the hidden-charm hidden-charm dipiondipion decays of decays of higher charmonia or higher charmonia or

higher bottomoniahigher bottomonia

Dian-Yong Chen, Dian-Yong Chen, Xiang Liu, , PRD84, 034032 (2011)PRD84, 034032 (2011)

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Dian-Yong Chen, Xiang Liu, Takayuki. Matsuki, PRD84, 074032 (2011)PRD84, 074032 (2011)

PredictedPredicted chargedcharged bottomonium-like bottomonium-like

structuresstructures near near BB* BB* and B*B* thresholdand B*B* threshold..

Belle II and SuperBBelle II and SuperB

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BESIIIBESIII

Belle&BaBarBelle&BaBar

Belle IIBelle II

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CLEO-c, PRL107, 041803 (2011)

Dian-Yong Chen, Xiang Liu, Phys. Rev. D84, 034032 (2011)Phys. Rev. D84, 034032 (2011)

MeV 4170@ chee MeV 4260@/ Jee

ISPE Mechanism

Bottomonium Charmonium Strangeonium

A series in flavor:

M=2.175 GeV Γ= 58 MeV

PRD74,091103(R) (2006) PRL100,102003 (2008)

BES-IIM=2.186 GeV Γ= 65 MeV

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)2175(Y )1860(

• Similar novel peak structures• K*K : Sharp & Narrow K*K* : Smooth& Broad • More Experimental Measurements (BESIII)

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SummarySummary

• Non-resonant explanationNon-resonant explanation to to Y(4260)Y(4260) and and Y(4360)Y(4360)

• Charged Charged ZZbb(10610)(10610) and and ZZbb(10650)(10650)

MechanismMechanism ：： ISPE mechanismISPE mechanism

Extend to Charmonium, StrangeoniumExtend to Charmonium, Strangeonium

• More More effortsefforts theorytheory++experimentexperiment

Belle-II,Belle-II, BESIIIBESIII,, LHCb, SuperB, PANDALHCb, SuperB, PANDA

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Thank you Thank you ！！

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A series in flavor:

ISPE Mechanism

Bottomonium Charmonium Strangeonium

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M=2.175 GeV Γ= 58 MeV

PRD74,091103(R) (2006) PRL100,102003 (2008)

BES-IIM=2.186 GeV Γ= 65 MeV

Process M(GeV) Γ(MeV)

BaBar(2006) 2.175 58

BES-II(2008) 2.186 65

Belle(2009) 2.127 60

Belle(2009) 2.079 192

BES-II

ee

ee

)980(0fee

)980(/ 0fJ

0*0*/ KKJ No Evidence of Y(2175)

Summary of Mass of width