1. Coupled-channel effects in the decays of exotic states
Gang Li
Department of Physics, Qufu Normal University
In Collaboration with: X.-H. Liu, F.-L. Shao, W. Wang and Q. Zhao
中国物理学会高能物理分会第九届全国会员代表大会暨学术年会 2014年4月18日--23日

2. Outline 1. Present status of exotic states
2. Coupled-channel effects in the decays of exotic states
3. Summary

3. Charged exotic states observed in experiments

4. Zb(10610) and Zb(10650)

5. Charged Charmonium-like states discovered in 2013
BESIII, Phys.Rev.Lett. 110, (2013).
Belle, Phys.Rev.Lett. 110, (2013).

6. BESIII, Phys.Rev.Lett. 112,   (2014).
BESIII, Phys.Rev.Lett. 111, (2013).

7. BESIII, Phys.Rev.Lett. 112,   (2014).

8. Belle, Phys.Rev.Lett. 108, (2012).
BESIII, Phys.Rev.Lett. 110, (2013).
Belle, Phys.Rev.Lett. 110, (2013).
BESIII, Phys.Rev.Lett. 112,   (2014).
BESIII, Phys.Rev.Lett. 111, (2013).
BESIII, Phys.Rev.Lett. 112,   (2014).
Masses of these exotic candidates are very close to their corresponding two-particle thresholds.

9. Explanations on these exotic states
Zb(10610) and Zb(10650)
◆ Molecular states
N. Li et al. Phys.Rev. D88, (2013);
Z.-W. Liu et al ;
A. E. Bondat et al. Phys. Rev. D 84, (2011);
J.-R. Zhang et. al. Phys.Lett.B704, 312 (2011);
Z.-F. Sun, et al. Phys. Rev. D 84, (2011); ……
◆ Tetraquark
T. Guo et al ;
C.-Y. Cui et al. Phys. Rev. D85, (2011)
◆ Cusp effect of BB* and B*B*
Bugg, Europhys. Lett.96:11002 (2011)

10. Zc(3900)/Zc(3885) and Zc(4025)/Zc(4020)
◆ Molecular states
Q. Wang, C. Hanhart, Q. Z, Phys. Rev. Lett. 111, (2013); Phys. Lett. B725, (2013); F.-K. Guo, C. Hidalgo-Duque, J. Nieves, and M. P. Valderrama, Phys. Rev. D 88, (2013); D.-Y. Chen, X. Liu, and T. Matsuki, Phys. Rev. Lett. 110, (2013); M. Karliner and S. Nussinov, J. High Energy Phys. 07 (2013) 153; C.-Y. Cui, Y.-L. Liu, W.-B. Chen, and M.-Q. Huang, arXiv: ……
◆ Tetraquark
L. Maiani, V. Riquer, R. Faccini, F. Piccinini, A. Pilloni, and A.D. Polosa, Phys. Rev. D 87, (R) (2013);
◆ Hadro-quarkonium
M. B. Voloshin, Phys. Rev.D87, (R), 2013； N. Mahajan, arXiv:

11. Talk from Prof. Zhu’s talk

12. Coupled-channel effects have been extensively studied in the production and decays of ordinary states and exotic state candidates
◆ Q. Wang, C. Hanhart and Q. Zhao, Phys. Rev. Lett. 111, (2013); F. -K. Guo, C. Hanhart, U. -G. Meißner, Q. Wang and Q. Zhao, Phys. Lett. B 725, 127 (2013); Q. Wang, C. Hanhart and Q. Zhao, Phys. Lett. B 725, no. 1-3, 106 (2013); M. Cleven, Q. Wang, F. -K. Guo, C. Hanhart, U. -G. Meißner and Q. Zhao, Phys. Rev. D 87, no. 7, (2013).
◆ D. -Y. Chen, X. Liu and T. Matsuki, Phys. Rev. D 84, (2011); D. -Y. Chen, X. Liu and T. Matsuki, arXiv: [hep-ph]; D. -Y. Chen, X. Liu and T. Matsuki, Phys. Rev. D 88, (2013); D. -Y. Chen, X. Liu and T. Matsuki, Phys. Rev. D 88, (2013); D. -Y. Chen and X. Liu, Phys. Rev. D 84, (2011).
◆ M. B. Voloshin, Phys. Rev. D 87, no. 7, (2013);M. B. Voloshin, Phys. Rev. D 84, (2011).
◆ A. E. Bondar, A. Garmash, A. I. Milstein, R. Mizuk and M. B. Voloshin, Phys. Rev. D 84, (2011).
◆ G. Li, F. -l. Shao, C. -W. Zhao and Q. Zhao, Phys. Rev. D 87, no. 3, (2013); X. -H. Liu and G. Li, Phys. Rev. D 88, (2013); G. Li and X. -H. Liu, Phys. Rev. D 88, (2013).
…….

13. Quark-level descriptions of hadronic loop mechanism

14. Coupled-channel effects in Zb(10610), Zb(10650) decays
G. Li, F. -l. Shao, C. -W. Zhao and Q. Zhao, Phys. Rev. D 87, (2013)
Introduce tri-monopole form factors to kill the divergence and also compensate the off-shell effects of intermediate mesons

15. Effective Lagrangians
R.Casalbuoni et al., Phys. Rep. 281, 145 (1997).
P.Colagelo et al., Phys. Rev. D69, (2004).

16. Coupling constants R. Casalbuoni et al., Phys. Rep. 281, 145(1997).
H. Y. Cheng et al., Phys.Rev. D71, (2005).
D.Becirevic, et al., Phys.Lett.B679,231(2009).

17. The relatively stable dependence of the branching ratios indicates a reasonable cutoff of the ultraviolet contributions by the empirical form factor.
The enhanced branching ratios for suggests that more stringent dynamic constraints are presumably needed to describe the near-threshold phenomena where the local quark-hadron duality has been apparently violated

18. We determine the cutoff parameter for each channel separately by the experimental data and find it is possible to find an appropriate range of alpha values for each decay channels that can account for the data via the intermediate bottomed meson loops.
We make an average of the values for the Zb and Zb’ decays separately without including channel and find it is possible to describe the experimental data with single alpha values for Zb and Zb’, respectively.

19. Coupled-channel effects in Zc(3900), Zc(4025) decays
G. Li, Eur. Phys. J. C73, 2621 (2013)

21. Coupled-channel effects in isospin conserved decays of Z_Q and Z_Q’

25. Hunting for the Xb via Radiative Decays
G. Li, W. Wang, arXiv:

28. Thanks for your attention !
Summary
The decay channels of exotic state candidates are studied in intermediate heavy meson loops.
The alpha dependence of the branching ratios are relatively stable,
which indicate the dominant mechanism driven by the intermediate
meson loops with a fairly well control of the ultraviolet contributions.
Coupled-channel effects play an important role in the decays of exotic states, especially when the final state mass are close to the intermediate meson pair thresholds.
Thanks for your attention !