1. Kraków, June 9th, 2015 Exotic quarkonium-like states Andrzej Kupsc Positronium – quarkonia XYZ studies at BESIII Zc states: Zc 0± (3900), Zc 0± (4020) X(3872), Y(4260), Zc(3900) states: connections / transitions Outlook: structures in ππ(ss) ?

2. ”Leptonia” Δ E= 4·10 -5 eV Δ E= 8·10 -4 eV 1 S 0 para Ps L=0  ( → 2γ τ=1.2x10 -10 s) 3 S 1 ortho Ps L=0  ( → 3γ τ=1.4x10 -7 s) true muonium (μ + μ - ) BS positronium (e + e - ) BS

3. e + e - → hadrons pp → μ + μ - X LHC √s J PC =1 -- BESIII Belle BaBar c b

4. Charmonia (cc) BS November 1974

5. Charmonia above DD threshold

6. X(3872) Motivation: search for predicted missing narrow tensor charmonium state 1 3 D 2 J PC = 2 -- Ψ 2 Phys. Rev. Lett. 89, 162002 (2002) a loosely bound D D ∗ “molecular state,” ? Soo-Kyung Choi et al (Belle) >1000 citations PRL,91,262001 (2003) very narrow (< 1.2 MeV) Mass 3871.69±0.17 MeV close to D * 0 D 0 threshold (~3871.8) J PC = 1 ++ (LHCb) PRL110,222001 (2013)

7. X(3872) Slide: XiaoLong Wang Confirmed immediately by Babar, CDF,D0, …, LHCb

8. Z(4460)  π ± ( cc) first tetraquark state PRL112 (2014) 222002 Soo-Kyung Choi et al (Belle) PRL,100,142001 (2008) Confirmed 2014 by LHCb

9. Y(4260) e+e−  π+π-J/Ψ (ISR) BaBar: (2005). PRL 95, 142001 (2005) Y states: J PC =1 -- (could be directly produced in e+e- colliders) Y(4260) observed in π+π−J/ψ system (BaBar) confirmed by CLEOc and Belle. Exotic properties: Not expect cc state  already too many states strongly coupled to ππJ/ψ and suppressed to open charm

10. Belle: C. Z. Yuan et al., PRL99,182004(2007 ) CLEO-c Y(4260)

11. e + e - → π + π - J/ψ at Y(4260) peak 0.5fb -1 @4.26 GeV Collected winter 2012/2013

12. Significance >8σ Significance >5.2σ Significance >5σ Observation of Z c ± (3900) in e+e- → π+π-J/ψ Couples to cc Has electric charge => At least 4-quarks CLEO-c data Spring 2013 BESIII: PRL 110 252001 BELLE: PRL 110 252002 CLEO-c data: PLB 727, 366

13. Nature of Zc(3900) and observation of Zc(4020)

14. 3.5σ CLEO-c data New BESIII data: 2.8 fb -1 at 10 energies: 4.26 – 4.42 GeV Zc 0 (3900) observed with significance >10.4 σ Observation of Zc 0 (3900) in e+e- → π 0 π 0 J/ψ

15. Preliminary yields of Zc 0 (3900), at 10 energy points: M = 3894.8±2.3 MeV Γ= 29.6±8.2 MeV Preliminary parameters extracted from simultaneous fit to the π 0 J/ψ invariant mass distributions for: 4230 MeV, 4260 MeV and 4360 MeV subsamples. Observation of Zc 0 (3900) in e+e- → π 0 π 0 J/ψ

16. Observation of Zc 0,± (4020) in e+e- → ππh c (1P) PRL 113 (2014) 21, 212002

17. e+ e− → γX(3872) → γπ+ π− J/ψ PRL 112 092001 (2014) M = (3871.9±0.7±0.2) MeV, Γ<2.4 MeV, Significance:6.3σ data suggest production in Y(4260) decay

18. arXiv:1411.5997 What is nature of these states? – Tetraquark – Hadronic molecule – Hadro-charmonium – Meson loop – ISPE model Analogous bottomonium-like structures What about strangeonium system?... JP 1 + ? ? π±,π0 π±,π0 γ Pictures: http://www.wired.com/2014/09/tetraquark-quantum-feud/ I= 1 Summary Dipositronium Ps 2 Nature 449, 195 (2007) 0.4 eV

19. Y(2175) / φ(2170) BaBar PRD 74, 091103 (2006) BESIII, PRD91 (2015) 052017 Belle PRD 80, 031101 (2009) BES PRL 100 (2008) 102003 (ss) BS (ππ)(ss)