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 2011.3.18-20, Beijing

Outline Charnomium-like states XYZ Y(4260) and Y(4360) Experimental observations Theoretical status Non-resonant explanation for Y(4260) and Y(4360) Summary Xiang Liu @ LZU

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. Xiang Liu @ LZU

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) Xiang Liu @ LZU

Y(4260) and Y(4360) Y(4260) Spin-parity: J =1 PRL95, 142001 (2005) PC -- Xiang Liu @ LZU

Y(4360) Spin-parity: J =1 PRL98, 212001 (2007) PRL99, 142002 (2007) PC -- PRL98, 212001 (2007) PRL99, 142002 (2007) M=4324±24 MeV Γ=172±33 MeV M=4361±9±9 MeV Γ=74±15±10 MeV Xiang Liu @ LZU

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. Xiang Liu @ LZU

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 Xiang Liu @ LZU

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 Xiang Liu @ LZU

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, 092001 (2007) PRL101,172001(2008) DD*π arXiv:0908.0231 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 Xiang Liu @ LZU

Non-resonant explanation for Y(4260) and Y(4360) The interference between Continuum and Resonance Xiang Liu @ LZU

Background Y(4360) Y(4260) Xiang Liu @ LZU

Can we reproduce the line shape of Y(4260) and Y(4360) in our model? Five fitting parameters: Xiang Liu @ LZU

Numerical results for Y(4260) D.Y. Chen, J. He and Xiang Liu, Phys.Rev.D83, 054021 (2011) Y(4260) Y(4008) M=4008±40 MeV Г=226 ±44 MeV Belle, Phys.Rev.Lett.99:182004 (2007) Xiang Liu @ LZU

Numerical results for Y(4360) D.Y. Chen, J. He and Xiang Liu, arXiv:1101.2474 Xiang Liu @ LZU

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)  Xiang Liu @ LZU

Thank you for your attention! Xiang Liu @ LZU