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Qiang Zhao Institute of High Energy Physics, CAS

This symposium discusses observations and dynamics of exotic particles in high-energy physics, covering forbidden configurations, potential molecules, scalar puzzles, and glueball mixing. It delves into topics like pseudoscalar spectrum puzzles, charmonium-like states, and the charged charmonium spectrum, exploring new physics scenarios. The event presents groundbreaking research and findings in the field of high-energy physics.

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Qiang Zhao Institute of High Energy Physics, CAS

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  1. Institute of High Energy Physics Open threshold phenomena Qiang Zhao Institute of High Energy Physics, CAS and Theoretical Physics Center for Science Facilities (TPCSF), CAS zhaoq@ihep.ac.cn 2015强子物理核与物理前沿研讨会，2015.01.10-11, UCAS,Beijing.

  2. Outline 1. Observations of exotic candidates 2. Learn dynamics from systematics 3. Brief summary

  3. 1. Observations of exotic candidates

  4. Exotics of Type-I: JPC are not allowed by QQ configurations For states in natural spin-parity series P=(1)L+1 =(1)J , the state must have S=1 and hence CP=(1)(L+S)+(L+1) =+1. Therefore, mesons with natural spin-parity but CP= 1 will be forbidden, e.g. 0+, 1+, 2+, 3+, … L + Natural: 0++, 1, 2++, 3, … Unnatural: ( 0), 1++, 2,3++, …  S=1 L + Unnatural: 0+, 1+, 2+, 3+, …  S=0

  5. Exotics of Type-II: JPC are the same as QQ configurations qq SU(3) flavor nonet:33 =18 S JPC = 0 K0 (sd) K (su) 1 I3 –1 1 – (ud) +(du) 0, ,  1 K(us) K0 (ds)

  6. qq SU(3) flavor nonet:33 =18 f0(1500) ? a1(1420)? (1405) ? Still exist a lot of puzzling questions!

  7. `qq tensor nonet puzzling scalar nonet `qq , `q2q2 , meson molecule ? a0(980) `uu -`dd , [`us`su -`ds`sd ] f’2(1525) `ss f0(980) `ss , [`su`us +`sd`ds ] K2(1430) `sd k(800) `sd , [`su`ud ] a2(1320) `uu -`dd f2(1270) `uu +`dd f0(600) `uu +`dd , [`ud`du ] Scalar puzzle (I): Scalars below 1 GeV: Pay less price to create a 0 qq pair instead to orbitally excite a qq?

  8. Scalar puzzle (II): Scalars above 1 GeV Lattice 0++: 1.5 ~ 1.7 GeV Exp. Scalars: f0(1370) f0(1500) f0(1710) f0(1790) (?) f0(1810) (?) f0 • Glueball-qq mixing? • Among f0(1370), f0(1500) and f0(1710), which is more sticky? Lattice QCD prediction Morningstar and Peardon, PRD (1999); Chen et al. PRD (2006)

  9. Pseudoscalar spectrum:“(1405)/  (1475) puzzle” – One state or two states？ 33 =18 S There is evidence for 3 states around 1.2 ~ 1.5 GeV, i.e. (1295), (1405), (1475). K0 K (1460) 1 1st radial excitation I3 (1405)cannot be accommodated in the qq scenario! –1 1 – +(1300) 0, (1295), (1475) 1 K(1460) K0(1460)

  10. “a0(980)-f0(980)mixing”gives only 1% isospin violation effects！   K0 (K) g(a0KK)g(f0KK) g(a0K0K0)g(f0K0K0) M(K0)M(K)  mdmu (1405) a0(980) f0(980)  K0 (K) I1 I0 “Triangle singularity” InternalKK*(K) approach the on-shell condition simultaneously! f0(980) K K K0K0  K* (1405/1475) K  K f0(980)  A novel isospin breaking mechanism!

  11. “三角奇异性”导致同一个态(1440)在不同衰变道表现出不同的“峰值”和“线型” (1405/1475) (1405/1475)   (1405/1475)   (1405/1475)  KK  -- (1405)和(1475)可能只是同一个态在不同衰变道中的反映！ • Looking for pseudoscalar glueball? • Wrong place for wrong signal！ • X(1835)? Or other higher states? J.J. Wu, X.H. Liu, Q.Z. and B.S. Zou, PRL108, 081803 (2012).

  12. The puzzle of f1(1420) and a1(1420) Relative S wave

  13. Partial wave analysis of J/   (1405)/f1(1420)    Dashed: eta(1440) Dotted: f1(1420) Solid: eta(1440) + f1 BESIII results:

  14. Implication of existence of a1(1420) Due to the “triangle singularity”, the same “state” produces different resonance-like lineshapes in different channels!

  15. Observation of a new state a1(1420) at COMPASS

  16. Ds spectrum in comparison with potential model calculations

  17. New charmonium-like states, i.e. X, Y, Z’s, are observed in experiment Zc(4200) Zc(4020) Zc(3900) Reveal a completely new scenario of strong QCD !

  18. Charged charmonium observed by BESIII e+  Y(4260)  (4415) e D*D1 Zc(3900) J/ Y(4360) DD1 Charmonium spectrum Y(4260) At least 4 quarks !  (4160) (4040) Zc(3900) DD* (3770) DD (3686)  J/ JPC = 1

  19. Y(4260) may have a sizeable DD1(2420) molecule component due to the strong S-wave coupling. D (cq), JP=0; D*(cq), JP=1; D1(cq), JP=1. Y(4260) DD* DD1(2420) W= 4020 MeV W= 4289 MeV D1  D1(2420) Y(4260), 1 Y(4260) D* D  D(1868) J/  Possible Explanation for the mysterious property of Y(4260)! Q. Wang, C. Hanhart and Q.Z., PRL111, 132003 (2013); Q. Wang, et al., PRD 89, 034001 (2014); F.-K. Guo, et al., PLB 725, 127 (2013); Q. Wang, et al., PLB 725, 106 (2013).

  20. Belle, arXiv:1105.4583[hep-ex]; PRL108, 22001 (2012) Heavy quark symmetry breaking?

  21. (5S)→B*B(*)π: Results Branching fractions of (10680) decays (including neutral modes): BBp < 0.60% (90%CL) BB*p = 4.25 ± 0.44 ± 0.69% B*B*p = 2.12 ± 0.29 ± 0.36% Assuming Zb decays are saturated by the already observed (nS)π, hb(mP)π and B(*)B* channels, one can calculate complete table of relative branching fractions: NEW! Belle PRELIMINARY B(*)B* channels dominate Zb decays ! A. Bondar at ICHEP2012

  22. 2. Learn dynamics from systematics

  23. Breakdown of potential quark model Linear conf. V(r) = /r   r qq creation Coulomb • Color screening effects? String breaking effects? • The effect of vacuum polarization due to dynamical quark pair creation may be manifested by the strong coupling to open thresholds and compensated by that of the hadron loops, i.e. coupled-channel effects. E. Eichten et al., PRD17(1987)3090 B.-Q. Li and K.-T. Chao, Phys. Rev. D79, 094004(2009); T. Barnes and E. Swanson, Phys.Rev. C77 (2008) 055206

  24. In case that hadronic molecules can be formed by mesons, the following points should be recognized: • The constituent mesons are in a relative S wave. • Similar to the nuclear force, the long range interaction may play a crucial role. • Different from the nuclear force, the nuclear repulsive core is not obvious. The role of the annihilation potential is not clear. • The open threshold has strong impact on the spectrum. • -- How to stabilize the hadronic molecular states made of mesons? • -- How to recognize the molecular scenario in the spectroscopy? • -- Do we have a coherent picture for understanding those XYZ states in heavy quarkonium spectrum?

  25. In case that the open threshold coupled channels play a role, typical ways to include such an effect are via hadron loops in hadronic transitions Y.J. Zhang et al, PRL(2009); X. Liu, B. Zhang, X.Q. Li, PLB(2009) Q. Wang et al. PRD(2012), PLB(2012) “ puzzle” X.-H. Liu et al, PRD81, 014017(2010); X. Liu et al, PRD81, 074006(2010) Q. Wang et al, PRD2012 G. Li and Q. Zhao, PRD(2011)074005 F.K. Guo, C. Hanhart, G. Li, U.-G. Meissner and Q. Zhao, PRD82, 034025 (2010); PRD83, 034013 (2011) F.K. Guo and Ulf-G Meissner, PRL108(2012)112002 The mass shift in charmonia and charmed mesons, E.Eichten et al., PRD17(1987)3090 X.-G. Wu and Q. Zhao, PRD85, 034040 (2012)

  26. Y(4260)可能是由第一个S波DD1(2420)相互作用构成的强子分子奇特态 D (cq), JP=0; D*(cq), JP=1; D1(cq), JP=1. Y(4260) DD* DD1(2420) W= 4020 MeV W= 4289 MeV D1(2420) Y(4260), 1 Y(4260) D(1868)  可以解释Y(4260)众多奇特的性质！ Q. Wang, et al., PRD 89, 034001 (2014); F.-K. Guo, et al., PLB 725, 127 (2013); Q. Wang, et al., PLB 725, 106 (2013).

  27. Zc(3900)可以通过“三角奇异性”机制产生！ • [J.-J. Wu, X.-H. Liu, and Q. Zhao*, B.-S. Zou, PRL108, 081003 (2012)] Zc(3900), I,JP= 1, 1 J/ D*   D M(Zc)  M(D) + M(D*) = 3.876 GeV 需要对Zc(3900) 在e+e-  J/psi pipi, hc pipi, DD*pi等过程中的动力学产生机制开展系统研究。

  28. Further test of the Y(4260) and Zc(3900) properties in the cross section line shape measurement Belle BESIII D1D D1D M. Cleven, Q. Wang, F.-K. Guo, C. Hanhart, U.-G. Meissner, and Q. Z., PRD90, 074039 (2014).

  29. Prediction for the anomalous cross section line shape Data from Belle D1D

  30. Invariant mass spectra for D, D*, and DD* Signature for D1(2420) via the tree diagram. The Zc(3900) could have a pole below the DD* threshold. How to distinguish a pole generated by dynamics from kinematic effects?

  31. Threshold enhancement: kinematic effects or dynamic structures? One loop diag. Contact interaction T1 = • Can Zc(3900) be caused by pure kinematic effects? • Can Zc(3900) be a genuine state? • How about two loop contribution?

  32. Threshold enhancement: kinematic effects or dynamic structures? One loop diag. Contact interaction T1 = T2 = Strong elastic scattering amp. requires summation of all bubble diagrams which will inevitably generate a pole – A physical state must be present! Guo, Hanhart, Wang and Zhao, arXiv:1411.5584[hep-ph]

  33. 3. Brief summary • Re-think about the concept of exotics: • Why we haven’t seen so far exotics as a class of states in the spectrum? • Why most of those enhancement signals “intend” to only appear near open thresholds? • How can we put together all the exotic observations to form a single coherent scenario? • How should we interpret the strong QCD phenomena into hadronic D.o.F. measured in exp. ? • … …

  34. f0(1370)  is dominant over KK, , ;  nonstrange nn f0(1370) is clearly seen in J/  , but not seen in J/  . f0(1370) NO f0(1370)

  35. f0(1710) KK is dominant.  ss f0(1710) • Clear f0(1710) peak in J/  KK. • Nof0(1710) observed in J/   ! NO f0(1710)

  36. J/psi radiative decay into scalar glueball (L.Gui, et al, arXiv:1206.0125(hep-lat), PRL2012.) • Widths of J/psi radiative decay into glueballs from lattice QCD. • Favor f0(1710) as a glueball candidate. PDG: Br(f0(1710) KK)=0.36  Br(J/f0(1710))= 2.410-3 Br(f0(1710))= 0.15  Br(J/f0(1710))= 2.710-3 Glueball-qq mixing seems to be inevitable! Unquenched calculations are needed!

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