You-Chang Yang ( 杨友昌 ) Jialun Ping ( 平加伦 ) Chengrong Deng ( 邓成荣 )

1. Constituent quark model study of the exotic meson states You-Chang Yang (杨友昌) Jialun Ping (平加伦) Chengrong Deng (邓成荣) Zunyi normal college (遵义师范学院) HNP2013, 2013.7.17-22, Zhangjiajie, Hunan

2. Outline • Introduction • The chiral constituent quark model • Gaussian expansion method for few-body systems • Spectrum of the exotic states • Summary

3. Introduction Over the last ten years ，many new Charmonium- and Bottomonium-like states, called 'XYZ' states, have been discovered by Belle, BES, BaBar and others.However, the inside structure and properties of them are still unclear so far.

4. n2s+1LJ

5. Challenge the quark model

6. PRL100,142001, (2008) Phys. Rev. D 78,072004 (2008)

7. PDG 15.6σ 16.0σ PRL108, 122001 (2012), The Belle Collaboration arXiv: 1105.4583v3[hep-ex], arXiv: 1110.2251 [hep-ex]

8. 3875.1MeV 3876.6MeV CLEO-c data, arXiv:1304.3036 Belle, PRL 110, 252002 (2013) BESIII, PRL 110, 252001 (2013) The simplest quantum numbers assignment is The central mass of Z(3900) is about more than 20MeV above the threshold

9. Possible interpretation of the new XYZ states 1. Four-quark states • Molecular state It is a loosely bound sate of a pair of mesons near threshold. • Diquark-antidiquark structure 2. Hybrid statesThey are states with an excited gluonic degree of freedom. 3. Mixing of 2 and 4 quarks 4. Threshold effectsIt comes about from rescattering near threshold due to the interactions between two outgoing mesons.

10. The Hamiltonianof theChiral Constituent Quark Model The chiral partner, σ-meson, is also usually introduced, although its existence is still in controversy.

11. ChQM-I ChQM-II Vijande J, Fernandez F and Valcarce A, J. Phys.G31,481(2005)

12. The high precision numerical method based on Gaussian expansion method In two-body system, one expands spatial wave-function in terms of a set of Gaussian basis function with ranges in geometric progression. It reads For two-body system, the matrix element of <V(r)> can be easily analytic calculating as following E. Hiyama, Y. Kino, M. Kamimura, Prog. Part. Nucl. Phys. 51 223 (2003)

14. where The matrix element of V(r) is

15. {r1=0.1 fm, rn=2 fm, nmax=7}

16. The relevant coordinates in each set are defined as

18. Spectrum of the exotic states p,η, K,σ p, η, K,σ hidden color channel

20. Numerical results [10] Vijande J, Fernandez F and Valcarce A 2005 J. Phys.G31,481

23. 3 1 4 2 3 1 2 4 ZC(4020) ?

24. 3 1 2 4 Tensor potential

25. Summary • The candidate of Zc(3900) released by BESIII very recently do not found in our calculation. However, D∗D∗ with I ( JPC) = 1 ( 0++) is a bound state if we take into account the color coupling. It maybe a candidate of Zc(4020) reported by BESIII; • The bound states of BB*, B*B* with I(JPC)=1(1+-) are respectively good candidates for the charged bottomonium-like resonances Zb(10610) and Zb(10650). Thestates BB∗ With I ( JPC) = 0 ( 1+-) is a good candidates for Zb0(10610) ; • The color-singlet single-channel calculation also shows that the B∗B∗with I ( JPC) = 1 ( 0++), 1 ( 1+-),, 0 ( 2++) are bound states; • If the quark–antiquark interaction in color singlet can be extended directly to color octet by Casimir scaling , then the OGE interaction will be attractive between two color-octet clusters in some multi-quark systems. So it is inevitable to produce deeply bound states for hidden-bottom states.

26. Thanks !

27. Color Spin color magnetic interaction