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The quark model study of multiquark system

The quark model study of multiquark system. Jialun Ping, Hongxia Huang, Chengrong Deng Nanjing Normal University Fan Wang Nanjing University 2009.4.20. Outline. Motivation Dibaryon Tetraquark Summary. Motivation. Quark models: success in describing hadron properties

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The quark model study of multiquark system

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  1. The quark model study of multiquark system Jialun Ping, Hongxia Huang, Chengrong Deng Nanjing Normal University Fan Wang Nanjing University 2009.4.20 NSTAR 2009, Beijing

  2. Outline • Motivation • Dibaryon • Tetraquark • Summary NSTAR 2009, Beijing

  3. Motivation • Quark models: success in describing hadron properties Glashow-Isgur-Karl model: constituent quark model Bag model: …… • Hadron: baryon (qqq) and meson (qq): unique color structures two-body interaction: qqq a good approximation Casimir scaling λi•λj qq NSTAR 2009, Beijing

  4. NSTAR 2009, Beijing

  5. Hadron-hadron interactions and multi-quark states • Glashow-Isgur-Karl model  nucleon-nucleon interaction intermediate range attraction is missing. (σ-meson is introduced. ππ s-wave resonance? correlated two-πexchange doesn’t introduce enough attraction NPA637(1998) 395; PTP103(2000)351; PRC70(2004) 014002) • Multiquark states H-particle has been searched for 30 years, not found. Other exotics: d*, NΩ, ΩΩ,……, no confirmation. d’, disappeared, Θ, disappeared? tetraquark states? Something missing? NSTAR 2009, Beijing

  6. qqqq qqqqqq molecule states Multi- quark NSTAR 2009, Beijing

  7. Success and Limitations • The Hamiltonian and the wave functions used are very good approximation, for qqq and 。 Unique color structure • Multi-quark system: various color structures available What are the effects of various color structure? • Multi-quark system is indispensable for our understanding of QCD, especially the abundant color structures of QCD. • Multi-quark system needs new quark model • New states needs explanations. NSTAR 2009, Beijing

  8. Dibaryon • CELSIUS-WASA Collaboration ABC anomaly: pn → dπ0π0 or pn → dπ+π- JP= 1+ or 3+resonance? • M ∼2.39 GeV, width ∼ 90 MeV PPNP61(2008)276; PRL102(2009)052301 • Our group: d*(IJP=03+) PRC39(1989)1889; PRC51(1995)3411; NPA688(2001)871 NSTAR 2009, Beijing

  9. NSTAR 2009, Beijing

  10. QDCSM • Quark delocalization, color screening model: Quark delocalization: NSTAR 2009, Beijing

  11. NN Phase shift calculations • PRC79(2009)024001 QDCSM M=2357 MeV Γ=14+96 MeV ChQM M=2393 MeV Γ=14+136 MeV • PRC76(2007)065201 NSTAR 2009, Beijing

  12. Tetraquark • There is a long list of candidates of tetraquark states: f0(600), f0(980), X(1576), DsJ(2317), DsJ(2460), X(3872), Y(2175), Y(4260), Z(3930), …… • Constituent quark model success in describing the properties of baryon and meson generalized directly to study tetraquark states Casimir scaling: λi•λj reasonable? NSTAR 2009, Beijing

  13. NSTAR 2009, Beijing

  14. Lattice Calculation • The results from Lattice：PRL 86(2001)18 arXiv:0802.3500 r NSTAR 2009, Beijing

  15. String-like quark Model • Conventional quark model • The two-body confinement potential is replaced by T. Goldman and S. Yankielowicz, PRD 12(1975)2910. NSTAR 2009, Beijing

  16. Other parts of model Hamilton NSTAR 2009, Beijing

  17. NSTAR 2009, Beijing

  18. The Confinement of tetra-quark NSTAR 2009, Beijing

  19. Jacobi ordinates NSTAR 2009, Beijing

  20. Total wavefunction: Two channels: Orbital wavefunctions: NSTAR 2009, Beijing

  21. Numerical results for ssss • Energy Channel I: 2275MeV; Channel II: 2193MeV Channel coupling: 2178MeV • Naïve quark model: 2560 MeV • Chiral quark model: 2400 MeV • Spatial structure NSTAR 2009, Beijing

  22. Other states • Nonstrange tetraquark: IJPC=00++: The two lowest states: 587 MeV, 1019 MeV f0(600) f0(980) IJP=01-: The lowest state: 984 MeV • qsqs: JP=0+ : The lowest state: 1306 MeV JP=1- : The lowest state: 1715 MeV---X(1576) • ssss: JP=0+ : The lowest state: 1924 MeV JP=1- : The lowest state: 2176 MeV---Y(2175) • cqcq: JP=0+ : The lowest state: 3688 MeV JP=1- : The lowest state: 3938 MeV---Y(4008) • cscs: JP=0+ : The lowest state: 4078 MeV JP=1- : The lowest state: 4248 MeV---Y(4260) NSTAR 2009, Beijing

  23. Summary • NN scattering (IJ=03) shows resonance structure by including ΔΔ in QDCSM and chiral quark model. The resonance can be used to explain the ABC effect seen in reaction pn → dππ. • According to the suggestion of LQCD, a string-like quark model is proposed. They are the same as the conventional constituent quark model for ordinary baryon and meson. • In this model, f0(600) , f0(980), X(1576), Y(2175), Y(4008), Y(4260) can be interpreted as tetraquark states. • Multi-body interaction may be dispensable for multiquark state study. NSTAR 2009, Beijing

  24. Thanks! NSTAR 2009, Beijing

  25. NSTAR 2009, Beijing

  26. New color structure NSTAR 2009, Beijing

  27. Zero-order approximation NSTAR 2009, Beijing

  28. Numerical results • Single Channel calculation: Channel I: 2273 MeV; Channel II: 2216 MeV Channel coupling: 2196 MeV • It has similar energy as other color structures. • The coupling of different color structures is needed to account for the decay. It is difficult …… NSTAR 2009, Beijing

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