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Exploring Mesons and Glue in QCD Beyond Quarks: Tetraquarks and Exotic States

This article delves into the fascinating world of mesons and gluons in Quantum Chromodynamics (QCD) beyond traditional quarks, focusing on diquarks, tetraquarks, and exotic states such as pentaquarks. It discusses the OZI rule, flavor tagging in J/ψ hadronic decays, scalar glueball states, and the challenge of measuring and identifying these unique particles. The text also covers the Jaffe model of light scalar mesons, S-wave meson-meson interactions, and potential tetraquark candidates like D*K and Ds(cs*) states. Various theoretical conjectures and experiments related to tetraquarks, hybrids, and anomalous charmonium states are explored, shedding light on the complex dynamics of subatomic particles.

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Exploring Mesons and Glue in QCD Beyond Quarks: Tetraquarks and Exotic States

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  1. Diquarks, Tetraquarks, and no quarks (but no pentaquarks) “Diquarks,Tetraquarks, Pentaquarks and no quarks” The meson landscape Scalars and Glue in Strong QCD New states beyond Weird baryons: pentaquark problems “Exotics: what needs to be measured” 1

  2. OZI rule and flavor tagging in J/ hadronic decays Known ss*/nn* measure ss*/nn* Example of “known” ss*/nn* = 1– or 2+ “ideal” flavour states

  3. OZI rule and flavor tagging in J/ hadronic decays • In J/ hadronic decays, an  or Φ signal determinesthe or component, respectively.  OZI rule

  4. OZI rule and flavor tagging in J/ hadronic decays Works nicely for 2++ where BOTH are ideal 2++:(1520) 2++:(1270)

  5. OZI rule and flavor tagging in J/ hadronic decays Fails completely for 0^{++}!!!

  6. f0(1370) at BES • f0(1370) (uu*+dd*) clearly seen in J/  , but not seen in J/  . BES II Preliminary f0(1370) NO f0(1370) PWA 0++ components

  7. Leading diagram if 0+ meson contains qq* only

  8. Extra diagram if 0++ has glueball in its wavefunction

  9. Scalar Glueball and Mixing • Meson G ss*nn* • 1710 0.39 0.910.15 • 1500 - 0.650.33- 0.70 • 1370 0.69- 0.15 - 0.70 s G n LEAR/WA102 Meson pair decays

  10. Unusual properties off0(1370), f0(1500) f0(1710) Scalar Puzzle A consistent pattern in these two experiments can establish role of Scalar Glueball \psi \to 0^{++} V Challenge: quantify the predictions

  11. 4.Outside the Quark Model: TETRAQUARKS or MOLECULES

  12. I=1 vector : I=0JP =2+ 1+ 0+ 1700 1D: 1- 1460 2S: 1- 1270/1525 2+ ? qq* + Glueball 1285/1530 1+ [qq][q*q*] 0+ 1370/1500/1710 0+ 980/600 770 1S: 1-

  13. + + How can we tell if its this - - + Or this? -

  14. Jaffe model of light scalar mesons Strong QCD attraction of 3*c 3*f qq into 0+ diquark e.g. Maiani et al heavy and light flavours

  15. Inverted flavour multiplets 1- 0+ 1020 ss* 890 su* sd* 780 uu*+dd* 770 uu*- dd* 980 (uu*+dd*)ss* 980 (uu*- dd*)ss* 800 (su*)uu* (sd*)dd* 500 uu*dd* e.g.Tetraquarks v Hybrids: One swallow don’t make a summer. Need the whole flock/multiplet.

  16. New states outside the quark model:D_s(cs*) states that might beDK or tetraquarks

  17. DK

  18. D*K DK

  19. A conjecture: T.Barnes, F.E.Close, H.J.Lipkin, hep-ph/0305025, PRD. Reminiscent of Weinstein and Isgur’s KKbar molecules, bound by level repulsion of the KKbar continuum against higher mass qqbar 0+ scalars at ca. 1.3 GeV.

  20. 27 S-wave meson-meson beats P-wave qq* (continued) Whatever makes scalar f_0(980) light (= just below KK) (compared to qq* p-wave) Probably makes scalar 2317 light (= just below DK) (compared to qq* p-wave) …and 2460 axial light (just below D*K) Expt: Are there other cs* 0+ 1+ as well? (thy. confused) Production of two 1+ in B decays via W current Radiative transitions….

  21. New states outside the quark model that mightbe tetraquark:cc* X(3872) anomalous charmonium

  22. An extra narrow charmonium state Seen in B \to K X(3872)

  23. X(3872) mass compared with DD* thresholds DD* molecule “tetraquark” Mass = neutral threshold to better than 1 in 10,000 cuc*u* S-wave JPC = 1++ isospin maximally broken

  24. Close+Page Tornqvist Swanson

  25. 18 cc*1++ 3550; 1++* 3950: DD* (neutral) threshold Psi rho; psi omega P-wave cc* Mass coincidence only happens with Charm, not strange or bottom S-wave 1++ mesons Energy degeneracy will drive this >> model details. Psi rho:psi omega \sim 1 Deviations = dynamics Specific model: Swanson psi D D* uu* vector D* D pi Decays driven by meson-meson wavefunction Production by cc* residue: like psiprime D* D

  26. Molecule or radial 1++ cc*? • Suzuki: cc* with cc*uu* admixture(also FC+ Page) • Further tests: Production in B+ bigger than Bo Test: X \to K+K-\pi>> K0K0\pi CLEOc/BES precision test for 1++ 3550 also

  27. 5: HYBRID CHARMONIUM

  28. e.g. p=1 c.m. Gluonic hybrid mesons Exciting the flux tube

  29. e.g. p=1 c.m. Gluonic hybrid mesons Exciting the flux tube 2006:Lattice QCD seems to confirm flux tube model predictions !

  30. e.g. p=1 c.m. flux-tube degrees-of-freedom Costs about 1 to 1.5GeV energy to excite phonon “pi/R” Hybrid nn* @ 2GeV; Hybrid cc* @ 4-4.5GeV

  31. e.g. p=1 c.m. flux-tube breaking and decays Break tube: S+P states yes; S+S suppressed 1-+ \to pi b_1:pi f_1 = 4:1 and big FC Page95

  32. e.g. p=1 c.m. flux-tube breaking and decays Break tube: S+P states yes; S+S suppressed 1-+ \to pi b_1:pi f_1 = 4:1 and big FC Page95 QCD Lattice 06: Michael+McNeile confirm this !!?? Implies FT model estimates somehow mimic strong QCD Supports hybrid decay to S+P states

  33. e.g. p=1 c.m. flux-tube breaking and decays Break tube: S+P states yes; S+S suppressed S+S = 0 for hybrid charmonium (FC + Page) Look for DD_{0,1}; a bit of DD* and absence of DD or D*D* and of DsDs or Ds*Ds* \psi f_0; \psi pipi; \chi \eta; h_c \eta also

  34. More new anomalouscharmonium states:cc* 2++(3930) X(3940) Y(4260)Hybrids or tetraquarks?

  35. cc* 2++(3930) in gamma gammaprobably cc* radial chi_22P(^3P_2)X(3940) could be radial eta_c3S(^1S_0)+ possible anomalous statesX(3940) Y(4260)Hybrids or tetraquarks?

  36. ??? e+e- to + X Belle

  37. Inconsistent strengths? Belle and1+ ? radial ?? thresholds big ?

  38. Belle Y(3940) claimed “hybrid charmonium” ….but seems also to be in DD* (need to measure b.r)….

  39. Is this the same as X(3940)? Is it hybrid charmonium as claimed? ….probably not, but this might be…….

  40. e+e- \to psi pi pi BaBar sees new vector cc* Y(4260)

  41. Y(4260) Three Possibilities Y(4260) = Non resonant S-wave threshold Experimental distinctions….later

  42. But small relative to psiprime \Gamma(e+e-) 5 to 80 eV

  43. e+e- \to psi pi pi BaBar sees new vector cc* But width 90MeV dominantly psi pipi !

  44. f0(980)?

  45. All consistent with predictions for hybrid charmonium FC+Page 1995

  46. This is a clear distinction with hybrid for which this is ~ zero

  47. Is it really a resonance? e+e- DD_1 is first S-wave charm threshold and occurs \sim 4.2 GeV ! S-wave, relative mom \sim 0; DD_1 interchange constituents to make psi pipi “strongly” (c.f. Swanson model of 3872 DD* \to psi omega) psi D D_1 uu * pi pi e+e- Ds Ds_1 psi KK should show similar

  48. e+e- KK_1 Future need to do: Compare this with the DD_1 / psi pipi case: M(pipi); phi (psi) polarisation phi pi pi

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