Theoretical Progress on XYZ States Dian-Yong Chen Institute of Modern Physics, CAS Research Center for Hadron and CSR Physics Lanzhou University & Institute of Modern Physics of CAS Collaborated with Xiang Liu, Jun He, Shi-Lin Zhu, Xue-Qian Li, T. Matsuki

Outline Charmonium-like state Y(4260) Y(4360) Y(5S) hidden-bottom dipion decays Zb(10610) Zb(10650) Summary

Dian-Yong Chen, Jun He and Xiang Liu Charmonium-like states Y(4260) and Y(4360) Dian-Yong Chen, Jun He and Xiang Liu PRD83, 074012 (2011) PRD83, 054021 (2011)

According to the production mechanism, we can categorize these charmonium-like states X, Y, Z as four groups: ISR process Y(4260) Y(4008) Y(4360) Y(4630) Y(4660)

Experimental status of Y(4260) and Y(4360) PRL95, 142001 (2005) Y(4260) Spin-parity: J =1 PC --

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

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.

2 D1 state decay behavior  Eichten, Lane, Quigg 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

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

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

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

Background Y(4360) Y(4260)

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

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)

Numerical results for Y(4360) Dian-Yong Chen, Jun He and Xiang Liu PRD83, 074012 (2011)

Y(5S) hidden-bottom dipion decays Zb(10610) and Zb(10650) Dian-Yong Chen, Jun He, Xun-Qian. Li, Xiang Liu, PRD84, 074006 (2011) Dian-Yong Chen, Xiang Liu, Shi-Lin Zhu, PRD84, 034002 (2011) Dian-Yong Chen, Xiang Liu, PRD84, 094003 (2011) Dian-Yong Chen, Xiang Liu, PRD84, 034032 (2011) Dian-Yong Chen, Xiang Liu, Takayuki. Matsuki, PRD84, 074032 (2011) Dian-Yong Chen, Xiang Liu, Takayuki. Matsuki, preparing

Dipion hidden-bottom decays of Y(5S) Belle, PRL100, 112001 Belle, PRD82, 091106(R) (2010) Decay channel MeV 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 102 Puzzle existing in Y(5S) dipion hidden-bottom decays

Rescattering mechanism Explanations of anomalous branching ratios of Y(5S) hidden-bottom dipion decays Rescattering mechanism C. Meng, K.T. Chao PRD77, 074003 (2008) PRD78, 034022 (2008) PRD78, 074001 (2008) Yu. A. Simonov JETP Lett. 87, 147 (2008) H.W. Ke, Xiang Liu, X.Q. Li PRD82, 054030 (2010) Bottom analogue of Y(4260) s. Godfrey, S.L. Olsen arXiv:0801.3867 Exotic structure-Tetraquark state near Y(5S) M. Karliner, H.J. Lipkin arXiv:0802.0649 A. Ali et al. PLB684, 28 (2010), PRL104, 162001 (2010)

Indicate the mistake in Ali’s work Propose interference effect Ali et al., PRL104, 162001 Chen, He, Li, Liu, PRD84, 074006 (2011) Tetraquark explanation to Y(10870) Indicate the mistake in Ali’s work Propose interference effect New puzzle!

Experiment status of two charged Zb Belle Collaboration arXiv:1105.4583 Zb(10610) Zb(10650)

Zb structues and new puzzle Chen, Liu, Zhu, PRD84, 054002 (2011) Two newly observed Zb structures play important role to solve “new puzzle” in Y(5S)Y(2S)π+π- decay Question: what is the source to generate Zb(10610) and Zb(10650)?

Theoretical explanation I- Exotic strucutes S-wave BB* and B*B* molecular states Liu, Xiang Liu,Deng, Zhu, EPJC56, 63 (2008) Xiang Liu, Luo, Liu, Zhu, EPJC61, 411 (2009) Bondar, Garmash, Milstein, Mizuk, Voloshin, arXvi:1105.4473 Zhang, Huang, arXiv:1105.5472 QCD sum rule Voloshin, arXiv:1105.5829 Radiative decays Cleven, Guo, Hanhart, Meissner, EPJA, 47, 120 (2011) Sun, He, Xiang Liu, Luo, Zhu, PRD84:054002,2011 One-Boson-Exchange model Tetraquark state Yang, Ping, Deng, Zong, arXiv:1105.5935 Guo, Cao, Zhou, Chen, arXiv:1106.2284 Predict BB* molecular state

Theoretical explanation II- Mechanism D. V. Bugg, EPL96, 11002 (2011) Cusp effect Yu. A. Simonov, arXiv: 1106.1522 Dian-Yong Chen, Xiang Liu, PRD84, 094003 (2011) Initial single pion emission (ISPE) mechanism An underlying mechanism without introducing exotic explanation!

BB* BB Exp B*B*

BB* B*B* BB

Dian-Yong Chen, Xiang Liu, PRD84, 034032 (2011) More predictions Dian-Yong Chen, Xiang Liu, PRD84, 034032 (2011) If the ISPE mechanism is a universal mechanism in heavy quarkonium dipion decays, we naturally extend the ISPE mechanism to study the hidden-charm dipion decays of higher charmonia or higher bottomonia

Dian-Yong Chen, Xiang Liu, Takayuki. Matsuki, PRD84, 074032 (2011) Predicted charged bottomonium-like structures near BB* and B*B* threshold. Belle II and SuperB

BESIII Belle&BaBar Belle II

Dian-Yong Chen, Xiang Liu, Phys. Rev. D84, 034032 (2011) CLEO-c, PRL107, 041803 (2011)

A series in flavor: ISPE Mechanism Bottomonium Charmonium Strangeonium M=2.175 GeV Γ= 58 MeV PRD74,091103(R) (2006) PRL100,102003 (2008) BES-II M=2.186 GeV Γ= 65 MeV A series in flavor:

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

Summary Non-resonant explanation to Y(4260) and Y(4360) Charged Zb(10610) and Zb(10650) Mechanism：ISPE mechanism Extend to Charmonium, Strangeonium More efforts theory+experiment Belle-II, BESIII, LHCb, SuperB, PANDA

Thank you ！

A series in flavor: ISPE Mechanism Bottomonium Charmonium Strangeonium 34

Summary of Mass of width M=2.175 GeV Γ= 58 MeV PRD74,091103(R) (2006) PRL100,102003 (2008) BES-II M=2.186 GeV Γ= 65 MeV Summary of Mass of width Process M(GeV) Γ(MeV) BaBar(2006) 2.175 58 BES-II(2008) 2.186 65 Belle(2009) 2.127 60 2.079 192 BES-II No Evidence of Y(2175) 35