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Exotic Mesons from an experimental perspective

Exotic Mesons from an experimental perspective. S. Olsen 贵州大学 June 3 2008. The XYZ Mesons. Placed here by J PC. Y(4660).  (4415). M(MeV). Y(4360). Z + (4440). X(41 60 ).  (4160). Y(4260). c c2 ’. Y(3940).  (4040). X(3940). DD. X(3872).  (3770). ’. h ’ c. c c2.

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Exotic Mesons from an experimental perspective

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  1. Exotic Mesonsfrom an experimental perspective S. Olsen 贵州大学 June 3 2008

  2. The XYZ Mesons Placed here by JPC Y(4660) (4415) M(MeV) Y(4360) Z+(4440) X(4160) (4160) Y(4260) cc2’ Y(3940) (4040) X(3940) DD X(3872) (3770) ’ h’c cc2 cc1 hc cc0 J/ hc can’t all be accommodated in the charmonium spectrum JPC

  3. What are they? • L Maiani et al • PRD 71,014028 (2005) • T-W Chiu & TH Hsieh • PRD 73, 111503 (2006) • D Ebert et al • PLB 634, 214 (2006) • … • NA Tornqvist • PLB 590, 209 (2004) • ES Swanson • PLB 598,197 (2004) • E Braaten & T Kusunoki • PRD 69 074005 (2004) • CY Wong • PRC 69, 055202 (2004) • MB Voloshin • PLB 579, 316 (2004) • F Close & P Page • PLB 578,119 (2004) • X Liu • arXiv 0708..4167 • … • P Lacock et al (UKQCD) • PLB 401, 308 (1997) • SL Zhu • PLB 625, 212 (2005) • FE Close, PR Page • PLB 628, 215 (2005) • E Kou, O Pene • PLB 631, 164 (2005) • …

  4. Molecules? PDG: M(X3872) = MeV PDG: MD0 + MD*0 = 3871.8 ± 0.4 MeV Equal to 1 part in 10-4 Coincidence? Belle: M(Z4430) =4433 ± 5 MeV PDG: MD* + MD1 = 4432.6 ± 1.4 MeV

  5. arXiv: hep-ph/0308277 correct predictions arXiv: 07084222 But not 1+

  6. JP of the Z(4430)? p 1- qpl l- y’ l+ l- y’ l+ qkl 1+ 0- K JP=1+favored, but only @ ~2s level

  7. arXiv: 0801.3540 ” ”… arXiv: 0801.1616 ” ”

  8. Molecules/threshold effectsshould be near thresholds DD thresholds DSDSthresholds ?? ?? ?? Note: there is no p- or r-exchange between Ds states ?? some of the states are near thresholds, but this is not a universal feature

  9. Molecular picture may work for some XYZ states, but not all.

  10. Diquark –antidiquark? These should come in isospin- & SU(3)-multiplets where are the “partner states”? X+(3872) Xu(3872) Xd(3872) X-(3872) u d c c u d c c c c d u c c u d Expect: B+K-Xu B0K0Xd Bf(B0K-X+)Bf(X+p+p0J/y) ≈ 2 M(Xd)-M(Xu)= 2(md-mu)/cosq Bf(B-K-X0)Bf(X+p+p-J/y) 8±3 MeV L Maiani et al PRD 71,014028 (20050

  11. BKSX & BK±X comparison BaBar 0803.2838 K±mode K±mode KSmode KSmode DM = 0.22 ± 0.90 ± 0.27 MeV Compared to 8±3 MeV (Maiani et al PRD 71 014028) DM = 2.7 ± 1.6 ± 0.4 MeV

  12. no X±(3872) isospin partner is seen B0 K±p∓p0J/y B∓ KSp∓p0J/y ? ? Bf(B0K-X+)Bf(X+p+p0J/y) < 0.4 Bf(B-K-X0)Bf(X+p+p-J/y) (expect  2)

  13. None of the partner states required by the diquark-diantiquark picture have yet been seen.

  14. How about cc-gluon hybrids? c c • qq-gluon excitations predicted 30 yrs ago • LQCD: lowest 1-- cc-gluon mass ~4.3 GeV • - QCD sum rules get lower values ~3.7 GeV • relevant open charm threshold is D**D (~4.28 GeV) • G(ppJ/y) larger than that for normal charmonium • G(e+e-) for 1-- states less than ordinary charmonium Horn & MandulaPRD 17, 898 (1977) Y(4260) seems to match all of these!!! Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, 15713 (2003) Kisslinger et al, arXiv 0805.1943 (2008) Isgur, Koloski & Paton PRL 54, 869 (1985) McNeile, Michael & Pennanen PRD 65, 094505 (2002) Close & Page NP B443, 233 (1995)

  15. DD** thresholds in & “Y(4260)” D2D DD(**) thresholds D** spectrum D1D 4.7 4.5 No obvious distortions D D D 4.26 4.3 D 4.1 D 3.9 M(p+p-J/y) GeV D 3.7

  16. e+e-p+p-y’ peaks in Belle Two peaks! (both relatively narrow) (& both above all D**D thresh) (& neither consistent with 4260) M=4361  9 ±9 MeV G = 74  15 ±10 MeV M=4664  11 ±5 MeV G = 48  15 ±3 MeV Earlier BaBar values 4260 X.L. Wang et al (Belle) arXiv:0707.3699 PRL 99, 142002 (2007) M=4324  24 MeV G = 172  33 MeV 4360 4660 548 fb-1

  17. Y(4360) & Y(4660) are aboveall DD** thresholds D** spectrum 4.7 4.66 4.5 D D 4.36 D 4.3 D 4.1 D 3.9 D 3.7

  18. No signs in s(e+e- D0Dp) D0*(2400)D + D2*(2460)D 4360 4260 4660 100pb • Belle: G. Pakhlova et al, PRL 100, 062001 (2008)

  19. s(e+e- p+p-J/y) • C.Z. Yuan et al, PRL 99, 182004 (2007) ~60pb eyeball estimate

  20. s(e+e- p+p-y’) • X.L. Wang et al, PRL 99, 142002 (2007) ~70pb eyeball estimate ~40pb

  21. G(Y  p+p-J/y (y’)) are large BES: PRL 88, 101802 (2006) Belle (DD + DD* + D*D* + DDp) 4360 4260 4360 X.H. Mo et al, PLB640, 182 (2006): G(Y4260p+p-J/y)>10xG(y3770p+p-J/y)

  22. Data are in poor agreement with hybrid expectations Moreover, there are no charged charmonium hybrids, so these can’t account for the Z+(4430)

  23. Are there XYZ counterpartsin the ss- & bb- systems?

  24. (4S)  (1S) p+p- 2S 3S 4S is Huge!!! Belle:G((5S)pp(nS)) (4S)pp(1S) 477 fb-1 from Belle (1/20 times the data & ~1/10th the crosssection) 8 times as many events! “(5S)”pp(1S) 23.6 fb-1 from Belle 325±20 evts! 44±8 evts Belle 0710.2577 K.F. Chen et al (Belle) PRL 100, 112001 (2008)

  25. Partial Widths Assume “(5S)” = (5S) PDG value taken for (nS) properties N.B. Resonance cross section 0.302 ± 0.015 nb at 10.87 GeV PRD 98, 052001(2007) [Belle] >100 times bigger!! Cf (2S)  (1S)p+p- ~ 6 keV (3S) 0.9 keV (4S)1.8 keV

  26. (2S)p+p- (1S)p+p- p+p-(nS) Dalitz plots

  27. It looks like there is a bbversion of the Y(4260), the “Yb,”lurking around the (5S) (4S) (5S) Yb p+p-(nS) W.-S. Hou PRD 74, 017504 (2007)

  28. If there are bb versions of the XYZ’s, why not ss versions as well?

  29. 1-- Ys states around 2 GeV? ss equivalent of the J/y Y(2175)f0(980)f from BaBar e+e- g f0(980)h @ Ecm ~10.6 GeV BESII M(f0(980)f GeV M.Ablikim et al (BES) PRL 100, 102003 (2008)

  30. Maybe the X(1835) is one too? mostly ss J/ygX(1835) | p+p-h’ X(1835) M. Ablikim et al (BESII), Phys.Rev.Lett.95:262001,2005

  31. comments • There is a new meson spectroscopy not well explained as qq states • Maybe more than one • Bodes well for BESIII, Super-B factories & PANDA • Some states are narrow even though they are far above decay thresholds • e.g. Y(4660)ppy’ & Z+(4430)p+ y’ have large Q but G≈50 MeV • characterized by large partial widths (or Bfs) to hadrons+J/y (or y’) • Br(X(3872)rJ/y) > 4.3% (Isospin=1) • G(Y(3940)wJ/y) > 7 MeV • G(Y(4260)p+p-J/y) > 1.6 MeV • States that decay to y’ not seen decaying to J/y (and vice-versa) • Bf(Y(4660)ppy’) >> Bf(y(4660)ppJ/y)  same for Y(4360) & Z(4430py’ • Y(4260) not seen in Y(4260)ppy’ • The new 1-- states are not apparent in the e+e-D(*)D(*) cross sections • There are no evident changes at the D**D mass threshold • None of the existing ideas for non-qq mesons, i.e. molecules, di-quarks & hybrids, provide a natural explanation for the observed properties.

  32. Candidate models • Not all candidate states are close to thresholds. • None of the expected Ispin- or SU(3) partners are seen • No influence from DD** threshold observed • No possibility to accommodate the Z+(4430)

  33. Implications for BES-III • Search for charmonium-like states decaying to hc mesons • so far only J/y & y’ final states have been studied • At BES-III we have the possibility of clean hc signals

  34. For example: arXiv: 0805.4460 (last week) Accessible at BES-III?

  35. Implications for BES-III • Search for charmonium-like states decaying to hc mesons • so far only J/y & y’ final states have been studied • At BES-III we have the possibility of clean hc signals • Measure “open strangeness” decay modes for X(1835), Y(2175), etc • hybrid models say K1(1270)K &/or K1(1400)K should dominate • Systematic studies of final states including a f or an h’ • need to find patterns

  36. Example: p+p-h’ spectrum with 58M J/y’s 2 yrs @ BESII 2.5 days @ BES-III X(1835) M(’) GeV/c2 M(’) GeV/c2

  37. final comments

  38. 1963 Elementary particle “zoo” mesons +… baryons +…

  39. One good idea Gell-Mann Zweig mesons baryons ds us etc. du dd uu ud su sd

  40. 2008: a new “zoo” Y(3940) Y(4260) X(3940) X(4160) We need a new idea Y(4360) Y(4660) Z+(4430) Y(2175) X(1835)

  41. Summary • There is lots still to be learned about hadronic physics. • BES-III is well positioned in time & energy to contribute. • There are big challenges (& opportunities) for theorists.

  42. My advice to theorists present: • Think out of the box. • 加油

  43. 謝謝

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