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The XYZ mesons

The XYZ mesons. Stephen L. Olsen University of Hawaii PANIC-08 Nov 10-14, 2008 Eilat. (Decay to final states with a cc pair & S q i =0 ). X & Y mesons. X(3872). B  K p + p - J/ y. Y(4260). Belle. BaBar. e + e -  g ISR p + p - J/ y. Belle. Y(4008)?. M( p + p - J/ y)- M(J /y ).

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The XYZ mesons

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  1. The XYZ mesons Stephen L. Olsen University of Hawaii PANIC-08 Nov 10-14, 2008 Eilat

  2. (Decay to final states with a cc pair & Sqi=0 ) X & Y mesons X(3872) BKp+p-J/y Y(4260) Belle BaBar e+e-gISRp+p-J/y Belle Y(4008)? M(p+p-J/y)-M(J/y) Belle Y(3940) M(p+p-J/y) BaBar BKwJ/y Y(4350) & Y(4460) e+e-gISRp+p-y’ BaBar Belle M(wJ/y) M(wJ/y) M(p+p-y’) X(4160) X(3940) e+e-DD*J/y e+e-D*D*J/y e+e-gISRLcLc Belle Belle Belle M(LcLc) M(DD*) M(D*D*)

  3. Neutral cc X & Y mesons

  4. Are any of these standard cc charmonium? predicted measured

  5. Is the 1++ X(3872) the cc1’ (23P1) ? ?? 3872MeV • Mass is too low • cc1’ppJ/y violates Ispin • Bf(X3872ppJ/y)>4% • G(gJ/y) should be >>G(rJ/y) • expt: G(gJ/y) <<G(rJ/y)

  6. Neutral cc X & Y mesons It is pretty widely --but not universally-- accepted that the X(3872) is not a standard cc charmonium state. For a dissenting view, see C Meng & KT Chao PRD 75,114002 (2007)

  7. Could the Y(3940) be charmonium? True for all other BK(cc) transitions assuming Bf(BKY3940)<Bf(BKJ/y) = 1.0x10-3 G(Y3940wJ/y)>1MeV >10x higher than any measured cc hadronic transition

  8. Neutral cc X & Y mesons

  9. X(3940) & X(4160) = hc” &/orhc’’’ ? hc’’’ hc” 4160MeV 3940MeV One, or the other, could be the hc”, but it seems very unlikely that one is the hc” and the other is the hc’’’

  10. Neutral cc X & Y mesons ????? ?????

  11. σ(e+e–→open charm) DD ? DD* (4160) Y(4350) Belle: Sum of all measured exclusive contributions Y(4008) Y(4260) D*D* (4415) (4040) (3770) (4160) Y(4008) Y(4350) Y(4660) (4415) DDπ Y(4260) Y(4660) (4040) NEW Λc+Λc– Durham Data Base if Ruds=2.285±0.03 1-- ISR Y states not seen in D(*)D(*) G.Pakhlova et al (Belle): PRD 77, 01103 PRL 98,092001 PRL 100,062001 PRL 101,172001 This means that the ISR Y states have G(ppJ/y(y’)) > 1 MeV Too large for charmonium

  12. only 1 unassigned 1-- cc slot

  13. Neutral cc X & Y mesons ????? ????? ????? At most 1 of the 1-- Y states can be conventional cc charmonium

  14. The Z mesons Electrically charged counterparts of the X & Y mesons

  15. The Z meson candidates BKp+y’ 6.5  Z(4430) M2(p±y’) GeV2 M(p±y’) GeV S.-K. Choi et al (Belle) PRl 100, 142001 M2(Kp’) GeV2 BKp+cc1 >6  Z2(4250) M(p±cc1) GeV M2(p±c’c1) GeV2 Z1(4050) M2(Kp’) GeV2 R.Mizuk,R.Chistov et al (Belle) PRD 78, 072004

  16. Z meson properties d c Can’t be cc charmonium minimal quark content: ccud u c

  17. Still controversial Z(4430) not confirmed by BaBar (but neither do they rule it out). Belle A full Dalitz-plot analysis of the Belle BKp+y’ data will be reported at next month’s QWG meeting in Nara BaBar Arafat Gabareen Mokhtar talk at ICHEP-2008 B.Aubert et al (BaBar) arXiv/0811.0564

  18. What could theyXYZ states be?

  19. suggested possibilities(some references in backup slides) diquark-diantiquarks Expect SU(3) multiplets cc-gluon hybrids LQCD: M>~4.3 GeV Open charm thresh =MD+MD**4285 (above Y4260 peak) Non-zero charges are not allowed D(*)D(*) molecules (real or virtual) masses should be near M(D(*))+M(D(*)) mass thresholds Favored model for X3872 M(D0)+M(D*0)=3871.8±0.4 M(X3872)=3871.4±0.4

  20. Thresholds (*)(*) D(*)D(*) DSDS ?? No p exchng for DSDS some of the states are near thresholds, but this is not a universal feature

  21. no evidence for multiplet partners diquark-diantiquark expectations: 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

  22. no X±(3872) isospin partner is seen B0 K±p∓p0J/y B∓ KSp∓p0J/y BaBar BaBar ? ? Bf(B0K-X+)Bf(X+p+p0J/y) < 0.4 Bf(B-K-X0)Bf(X+p+p-J/y) (expect  2) B. Aubert et al (BaBar) PRD 71, 031501

  23. B0KSXd & BK±Xu with Xu=Xd? K±mode BaBar, arXiv: 0803.2838 Belle BaBar K±mode KSmode Belle KSmode BaBar 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

  24. PRL97,162002,2006 PRD77,011102,2008 NEW 6.4σ B+& B0D0D*0K 4.9σ B KD0D0p0 347fb-1 What about in the X3872DD* channel? M=3875.1 +0.7 ±0.5 M=3875.2±0.7 +0.9 -0.5 -1.8 Is this Maiani et al’s partner particle? ~4s higher than M in ppJ/y mode ~2s higher than M in ppJ/y mode

  25. B KD0D*0 D*→Dγ Preliminary D*→D0π0 605 fb-1 Flatte vs BW similar result: 8.8σ New results on X3872DD* from Belle More details in Tagir Aushev’s talk @ this meeting Agrees with M from ppJ/y mode M=3872.6 +0.5 ±0.4 MeV -0.4 N.Zwahlen, T.Aushev et al (Belle) arXiv/0810.0358

  26. 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)

  27. DD** thresholds and the Y(4260), Y(4360) & Y(4660) 4.66- 4285 D D 4.36- D Belle D 4.28- 4.26- 3.88- D 3.85- DD Y(4360) & Y(4660) well above all DD** thresholds

  28. Scoreboard ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??

  29. No model can accommodate all

  30. Are there XYZ counterparts in the b- and s-quark sectors?

  31. Y(4260) equivalent with b-quarks? Belle s(e+e- p+p-(nS)) Peaks not consistent with known bb states G(pp(nS) ~ 1000x too large for bottomonium K.F. Chen et al (Belle) arXiv:0808.2445

  32. Y(4260) equivalent with s-quarks? e+e-  g f0(980)f Y(2175)f0(980)f s(e+e- p+p-f(1020)) BaBar f0(980)p+p- M(f0(980)f)

  33. Confirmed by BES & Belle confirmed by BESII in J/y  h f f0(980) s(e+e- f0(980)f(1020)) BES Belle M(f0(980)f GeV X.L. Wang et al (Belle) arXiv: 0808.0006 M.Ablikim et al (BES) PRL 100, 102003 (2008)

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

  35. Concluding remarks • A number of “mysterious” mesons have been observed • They have large hadron-charmonium partial widths • Much larger than those seen in the charmonium system • There is no strong variations above DD** thresholds • As expected for cc-gluon hybrids • Some are near thresholds but not all • As expected for molecules, threshold cusps, etc. • No Isospin or SU(3) multiplet partners yet seen • As expected for diquark-diantiquark models • Similar structures in b- & (maybe) s-quark sectors

  36. However, none of the proposed models have produced a compelling match to the experimental observations

  37. Lots of pieces Y(3940) Z(4430) X(3940) Are they all from the same puzzle? X(4160) Y(4660) Y(4008) Y(4260) Y(4360) X(3872)

  38. Thank you

  39. Backup Slides

  40. Some recent reviews • Galina Pakhlova arXix:0810.4114 • This includes 64 references • See slides from her plenary talk @ ICHEP08 • S.-K. Choi arXiv:0810:3546 • See slides from her parallel talk @ ICHEP08 • E. Braaten arXiv:0808.2948 • 48 references, mostly on molecular-like models • S. Godfrey & S.L.O. arXix:0801.3867 • 128 references, but almost a year old

  41. Some theory references • 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) • H Lipkin & M Karliner • PLB 638, 221 (2006) • … c c • C Meng & KT Chao • PRD 75,114002 (2007) cc1’charmonium? • 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) • … too light?? P Lacock et al (UKQCD) PLB 401, 308 (1997)

  42. B-factories produce lots of cc pairs 0-+, 1-- or 1++ 0-+, 0++, 2++ 1-- only C =+ states

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