1. Xiang Liu Lanzhou University
Non-resonant explanation for charmonium-like states observed in ISR process
Xiang Liu
Lanzhou University
Symposium on the“12% rule” and “rho-pi puzzle” in vector charmonium decays
, Beijing

2. Outline Charnomium-like states XYZ Y(4260) and Y(4360)
Experimental observations
Theoretical status
Non-resonant explanation for Y(4260) and Y(4360)
Summary
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3. Charmonium-like states XYZ
In the past seven years, experiments reported many charmonium-like states X,Y, Z BaBar+Belle+CLEO+CDF
Stimulate theorist’s interest in revealying their underlying structures.
Hot topic in hadron physics at present.
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4. According to the production mechanism, we can categorized these charmonium-like states X, Y, Z as four groups:
ISR process
Y(4260)
Y(4008)
Y(4360)
Y(4630)
Y(4660)
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5. Y(4260) and Y(4360) Y(4260) Spin-parity: J =1 PRL95, 142001 (2005)PC
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6. Y(4360) Spin-parity: J =1 PRL98, 212001 (2007) PRL99, 142002 (2007)PC
PRL98, (2007)
PRL99, (2007)
M=4324±24 MeV
Γ=172±33 MeV
M=4361±9±9 MeV
Γ=74±15±10 MeV
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7. Theoretical explanation
Exotic state:
Y(4260)
Charmonium hybrid
Zhu, Kou&Pene, Close&Page
Diquark-antidiquark state [cs][cs] Maiani&Riquer&Piccinini&Polosa, Ebert& Faustov & Galkin
Molecular state ( )
Liu&Zeng&Li, Yuan&Wang&Mo, Qiao, Ding, Torres&Khemchandani
&Gamermann&Oset, Close&Downum&Thomas
Charmonium hybrid state with strong coupling with DD1 and D D0
Kalashnikova &Nefediev
The lack of signal in certain channels also poses a serious challenge to a number of the explanations proposed in the framework of an exotic state.
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8. 4S-3D vector charmonium Llanes-Estrada 2 D1 state decay behavior 
Conventional charmonium：
4S-3D vector charmonium Llanes-Estrada
2 D1 state decay behavior 
Eichten&Lane&Quigg
Mass spectrum Y(4260) ≠charmonium
Segovia&Yasser& Entem&Fernandez
Screened potential Y(4260) =Ψ(4S)
Li&Chao 3
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9. Conventional + exotic Y(4360) 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
Close&Downum&Thomas
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10. D*D*
DD*
ψ(4040)
ψ(4160)
Y(4008)
ψ(4415)
Y(4660)
Y(4260)
Y(4360) DD
DDπ
Λc+Λc– ?
PRD77,011103(2008)
PRL100,062001(2008)
PRL98, (2007)
PRL101,172001(2008)
DD*π
arXiv:
New
The main challenge of Y(4260) and Y(4360) as a conventional charmonium:
No evidence of Y(4260)/Y(4360) in the obtained open-charm process and R-value scan
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11. Non-resonant explanation for Y(4260) and Y(4360)
The interference between Continuum and Resonance
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12. Background
Y(4360) Y(4260)
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13. Can we reproduce the line shape of Y(4260) and Y(4360) in our model?
Five fitting parameters:
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14. Numerical results for Y(4260)
D.Y. Chen, J. He and Xiang Liu, Phys.Rev.D83, (2011)
Y(4260)
Y(4008)
M=4008±40 MeV Г=226 ±44 MeV
Belle, Phys.Rev.Lett.99: (2007)
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15. Numerical results for Y(4360)
D.Y. Chen, J. He and Xiang Liu, arXiv:
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16. Summary
Propose a nonresonant explanation for the Y(4260) and Y(4360) structures
Y(4260) and Y(4360) are not genuine resonances Y(4008)
Our explanation naturally answers why there is no evidence of Y(4260) and Y(4360) in the exclusive open-charm decay channel and R-value scan
Y(4630) and Y(4660)?
Y(4260) 
Y(4008) 
Y(4360) 
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17. Thank you for your attention!
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