1. The XYZ Mesons Stephen Olsen U. of Hawai’i & 高能所 北京 Nankai University 天津 April 7,2008

2. Constituent Quark Model (CQM) (& 6 antiquarks) Mesons: qq c:c: c +2/3 c:c: C -2/3  + : s -1/3 s +1/3 c -2/3 u -2/3 b +1//3 u +2/3  - : b -1/3 S =1/3 b +1/3 t -2/3 c +2/3 b -1/3 t +2/3 6 quarks Baryons: qqq u -2/3 d +1/3 s +1/3 u +2/3 d -1/3 s -1/3 Gell-Mann Zweig

3. Fabulously successful mesons q q

4. QCD suggests non-qq meson spectroscopies Glueballs: gluon-gluon color singlet states Multi-quark mesons: molecules: diquark-diantiquark: qq-gluon hybrid mesons d c d c cc d c dc

5. Caution Searching for non-QPM hadrons is a risky business 小心

6. Remember the pentaquark T.Nakano et al (LEPS) PRL 91 012002 (2003)  763 citations  + (1530)? forget

7. You never can be sure: or something else. Is mother nature is smiling at you?

8. The XYZ mesons: candidates for non-qq states cc uc u c 4 quark candidates (from Belle) “hybrid” qq-gluon candidates (from Babar & Belle)

9. Charmonium is of particular interest because it is an especially good system to use to search for non-qq mesons

10. Primer on Charmonium 小学课本

11. Charmonium r mesons formed from c- and c-quarks c-quarks are heavy: m c ~ 1.5 GeV  2m p velocities small: v/c~1/4 non-relativistic QM applies cc

12. QM of cc mesons cc r What is V(r) ?? “derive” from QCD

13. “Cornell” potential ~0.1 fm G.S.Bali hep-ph/0010032 “confining” large distance component slope~1GeV/fm 1/r “coulombic” short distance component cc r V(r) 2 parameters: slope & intercept

14. Charmonium spectrum

15. 1 -- Charmonium states J/  ’’ D-meson + anti-D meson mass threshold ”” “narrow” (  ~100KeV)  e+e+ e-e- Directly accessible via e + e - annihilation  (e + e -  hadrons) “narrow” (  ~300KeV) “wide” (  ~25 MeV)  ”  DD decay channel is open  DD)  25MeV  (4040)  (4160)  (4415)

16. P-wave states Gamma energy spectrum from  ’   X decays Gaiser et al (Crystal Ball) PRD 34 711 accessible via E1 transitions from  ’ 2 3 S 1 (  ’ )  1 3 P 2 (  c2 ) 17 keV 2 3 S 1 (  ’ )  1 3 P 1 (  c1 ) 24 keV 2 3 S 1 (  ’ )  1 3 P 0 (  c0 ) 24 keV 1 3 P 2 (  c2 )  1 3 S 1 (J/  ) 420 keV 1 3 P 1 (  c1 )  1 3 S 1 (J/  ) 290 keV 1 3 P 0 (  c0 )  1 3 S 1 (J/  ) 120 keV E1 Transition Partial width Calculable from”1 st principles” Good agreement with measurements

17. Hadronic transitions  (  ’      J/  )  70 keV “allowed”  (  ”      J/  )  50 keV “allowed”  (  ’   J/  )  5 keV SU F (3) violating     (  ’    J/  )  0.3 keV isospin violating “reasonable” agreement between measurement & theory c.f. Kuang & Yan PRD 41 155

18. Recent results 1 3 D 1   1 3 P 1 seen by CLEO hep-ex/0509030   (meas) = 75  18 keV  (theor)  59~77 keV 1 1 P 1 found by CLEO hep-ex/0508037 properties as expected 2 3 P 2 found by Belle hep-ex/0507033 properties as expected 2 1 S 0 found by Belle S.K.Choi et al PRL 89 102001 properties as expected

19. The potential model for cc charmonium mesons is robust and reliable

20. a cc meson has to fit into one of these slots: If it doesn’t, it is a good candidate for a non qq meson

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

22. Lots new on the “XYZ” particles X(3872) –     J/  in B  K     J/  Z(3930) –DD in   DD Y(3940) –  J/  in B  K  J/  X(3940) – e + e -  J/  X & e + e -  J/  DD* Y(4260) –     J/  in e + e -      J/  Y(4325) –  +  -  ’ in e + e -   +  -  ’ Y(4008)? Y(4250) Y(4370) Y(4660) X(3880)  DD - e + e -  J/  DD X(4160)  D*D* - e + e -  J/  D*D* Z + (4430)   +  - B  K  +  ’ New Belle/BaBar results: (Summer 2007) Status spring 2007: confirmed by BaBar updated by Belle

23. I’ll concentrate on recent results.

24. X(3872) >300 citations ’’ ’’ ’’ X(3872)

25. X(3872) properties (PDG2007) M D0 + M D*0 = 3.871.8 ± 0.4 MeV

26. M(  ) looks like     2 / dof = 43/39 (CL=28%) kinematic limit≈m  PRL 96 102002 CDF Belle Belle & CDF: J PC = 1 ++  most likely

27. What’s new with the X(3872)? BaBar confirms Belle’s DD  threshold enhancement Mass is 3.8 ± 1.2 MeV above WAvg X(3872)   J/  mass; (~3  is this significant? Both groups see a high mass value

28. Belle’s B  K S X & B  K ± X comparison  M = 0.22 ± 0.90 ± 0.27 MeV K S modeK ± mode “molecular” models predicted this to be <<1 (Braaten et al PRD 71 074005) “diquark-diantiquark” models predicted this to be 8±3 MeV (Maiani et al PRD 71 014028) Confirms an earlier BaBar result

29. Is there a cc slot for the X(3872)? 3872  M=3872 MeV is too low  Expect:  r  J/  >>Br(  J/  )  Meas:  r (  J/  )>>Br(  J/  ) 1 ++  (  c1 ’)   c    J/  ispin forbidden  D 0 D 0  0 @ thresh.suppressed  B  Kcc(J=2) suppressed 2 -+ (  c2 )

30. Y(3940) in B  K  J/  M≈3940 ± 11 MeV  ≈ 92 ± 24 MeV S.-K. Choi et al (Belle) PRL94, 182002 (2005) M(  J/  ) MeV M 2 (K  ) GeV 2 M 2 (  J  ) GeV 2

31. Y(3940) properties Belle PRL94, 182002 (2005) M(  J/  ) MeV  (Y 3940   J/  ) > 7 MeV ~ very large for charmonium the Y(3940) mass seems too high for it to be the  c1 ’

32. Confirmed by BaBar last summer B ±  K ±  J/  B 0  K S  J/  M 2 (K  )  J  ) ratio Some discrepancy in M &  ; general features agree B.Aubert et al (BaBar) arXiv 0711.2047

33. Is there a cc slot for Y(3940) ? Can M(  c1 ’)>M(  c2 ’)?  c1 ’ Mass is low c”c” “ “  c0 ’ 3940 3931 For any charmonium assignment,  [Y(3940)   J/  is too large.

34. Belle updates e + e -  J/  D ( * ) D ( * ) D(*)D(*) Use “partial reconstruction technique” reconstruct these J/  D(*)D(*) “Recoil” D ( * ) undetected (inferred from kinematics) Continuum e + e - annihilation e+e+ e-e-

35. J/  D ( * ) recoil mass J/  DD J/  DD* J/  D*D* J/  DD* Partial reconstruction reconstruct Belle arXiv:0708.3812

36. M(DD*): Confirm X(3940)  DD* D-reconstructed D * -tag D sidebands 6.0  Bg subtracted M = 3942 +7 ± 6 MeV  tot = 37 +26 ±12 MeV Nsig =52 +24 ± 11evts -6 -15 -16 Previous values: M = (3943 ± 6 ± 6) MeV  = (15.4  10.1) MeV  < 52 MeV at 90%CL PRL 98, 802001 (2007) arXiv:0708.3812

37. Is there a cc slot for X(3940) ? Mass is > M(  c2 ’) & no  c1 recoil seen  c1 ’ Mass is ~ 60 MeV low (if  (3S) =  (4040)) c”c”  c0 ’ 3940 3931 Mass is > M(  c2 ’) & DD decays not seen Maybe the  c ”

38. M(D*D*)  a new state at ~4160 MeV D*-reconstructed + D*- tag 5.5  M = 4156 +25 ± 15 MeV  tot = 139 +111 ± 21MeV Nsig =24 +12 ± 11evts -20 -61 -8 arXiv:0708.3812 It has to have C=+; most likely 0 -+,... possibly 0 ++ if 0 ++, why is it not seen in DD?

39. A cc assignment for X(4160) ? Mass is far too low (unless  (4S)=  (4160), but, then, where is  (2D?))  c ’’’ Mass is too high (if  (3S)=  (4040)) or too low (if  (3S) =  (4160)) c”c” 3940 3931 Can place either the X(3940) or X(4160), but probably not both. 4160

40. The 1 -- states seen in ISR

41. e + e -   isr Y(4260) at BaBar 233 fb -1 Y(4260) BaBar PRL95, 142001 (2005) ~50pb M=4259  8 +2 MeV  = 88  23 +6 MeV -6 -9 fitted values:

42. Not seen in e + e -  hadrons  (Y4260      J/  ) > 1.6MeV @ 90% CL X.H. Mo et al, PL B640, 182 (2006) 4260 BES data ~3nb  peak  Y(4260)  +   J/  pb Huge by charmonium standards J.Z.Bai et al (BES), PRL 88, 101802 (2006)  (e+e-  hadrons)  (e+e-   +  -)

43. “Y(4260)” at Belle (New) M=4247  12 +17 MeV  = 108  19 ± 10 MeV -32 M=4008  40 +114 MeV  = 226  44 ± 87 MeV -28 ??? C.Z Yuan et al (Belle) arXiv:0707.2541 PRL 99, 182004 M=4259  8 +2 MeV  = 88  23 +6 MeV -6 -9 BaBar values: Resonance? Thresh effect? …?

44. No 1 -- cc slot for the Y(4260) 4260 X.H. Mo et al, hep-ex/0603024

45. Is the Y(4260) a cc-gluon hybrid? cc qq-gluon excitations predicted 30 yrs ago lowest 1 -- cc-gluon mass expected at ~4.3 GeV relevant open charm threshold is D**D (~4.28 GeV)  (  J/  ) larger than that for normal charmonium  (e + e - ) smaller than that for ordinary charmonium Horn & Mandula PRD 17, 898 (1977) Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, 15713 (2003) Isgur, Koloski & Paton PRL 54, 869 (1985) McNeile, Michael & Pennanen PRD 65, 094505 (2002) Close & Page NP B443, 233 (1995) Y(4260) seems to match all of these !!!

46. DD** thresholds in & “Y(4260)” 4.28-m D D** spectrum M(     J/  ) GeV No obvious distortions D1DD1D D2DD2D

47. BaBar’s      ’ peak at 4325MeV Nbkg = 3.1  1.0 Nevt = 68 (<5.7 GeV/c 2 )  2 -prob < 5.7 GeV/c 2 Y(4260) 6.5  10 -3  (4415)1.2  10 -13 Y(4320)29% e + e -   ISR      ’ M=4324  24 MeV  = 172  33 MeV above all D**D thresholds S.W.Ye QWG-2006 June 2006 Not Compatible with the Y(4260) D1DD1D D2DD2D 298 fb -1 (BaBar) hep-ex/0610057 BaBar PRL 98 252001 (2007)

48. 4325 MeV      ’ peak in Belle (new) M=4324  24 MeV  = 172  33 MeV 548 fb -1 X.L. Wang et al (Belle) arXiv:0707.3699 PRL 99, 142002 (2007) Two peaks! M=4664  11 ± 5 MeV  = 48  15 ± 3 MeV M=4361  9 ± 9 MeV  = 74  15 ± 10 MeV BaBar values (both relatively narrow) (& both above D**D thresh) (& neither consistent with 4260) 4260

49. Recent News electrically charged!!

50. M(  ±  ’) from B  K  ±  ’ M 2 (K  ) GeV 2 M 2 (  ’ ) GeV 2 S.-K. Choi et al (Belle) arXiv:0708.1790 PRL 100 this Friday! K*  K  K 2 *  K  Veto M(  ’ ) GeV 6.5  M = 4433 ± 4 ±1 MeV  tot = 45 +17 +30 MeV Nsig =124 ± 31evts -13-11

51. Could this be a reflection from the K  channel?

52. Cos   vs M 2 (  ’ ) 16 GeV 2 22 GeV 2 M 2 (  ’) +1.0 cos   M (  ’) & cos   are tightly correlated; a peak in cos    peak in M(  ’) (4.43) 2 GeV 2 0.25 ’’  K 

53. Can interference between K  partial waves produce a peak? Only S-, P- and D-waves seen in data interfere Add incoherently

54. Can we make a peak at cos   ≈0.25 with only S-, P- & D-waves? Not without introducing other, even more dramatic features at other cos   (&, , other M  ’ ) values.

55. Comments on the Z + (4430) Not a reflection from the K  system ~ No significant signal in B  K  J/  It has non-zero charge  not cc or hybrid Mass, width & decay pattern similar to Y(4360) & Y(4660)

56. comments There seems to be a new hadron spectroscopy in the M=3.5~5 GeV region –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)   ’ & Z + (4430)     ’ have large Q but  ≈50 MeV characterized by large partial widths (Bfs) to hadrons+J/  (or  ’)  – Br(X(3872)   J/  ) > 4.3% (Isospin=1) –  (Y(3940)   J/  ) > 7 MeV –  (Y(4260)      J/  ) > 1.6 MeV States that decay to  ’ not seen decaying to J/  (and vice-versa) –Bf(Y(4660)   ’) >> Bf(y(4660)   J/  )  same for Y(4360) & Z(4430   ’ –Y(4260) not seen in Y(4260)   ’ 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 (mine)

57. New 1 -- states     J/      J/   ’ ’ C.-Z. Yuan et al (Belle) PRD 77, 011105® (2008)

58. some of the states are near thresholds, but this is not a universal feature D S D S thresholdsDD thresholds

59. D*D* DD* DD  tot Y(4660)Y(4360) Y(4260) Y(4008) The 1 -- states do not match well to peaks in hadr. cross-sections Pakhlova (Belle) PRL 98, 092001 (2007)

60. Are there XYZ counterparts for the ss- & bb- systems?

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

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

63. It looks like there is a bb version of the Y(4260 ) lurking around the  (5S) If there are bb versions of the XYZ’s, why not ss versions as well? W.-S. Hou PRD 74, 017504 (2007)

64. 1 -- Y s states around 2 GeV? Y(2175)  f 0 (980)  from BaBar (confirmed by BESII) e+e-   f 0 (980)  @ Ecm ~10.6 GeV confirmed by BESII M(f 0 (980)  GeV M.Ablikim et al (BES) PRL 100, 102003 (2008) 3 weeks ago

65. Luciano Maiani @ had-2007

66. Now it looks like there may also be XYZ-like spectroscopies for the s- & b-quark sectors

67. Lots of pieces Y(4360) Y(4660) Y(4260) Y(4050) X(3872) X(3940) X(4160) Z(4430) Y(3940) Are they all from the same puzzle?

68. 謝謝

69. Inclusive B  Kx from BaBar ? Fully reconstructed B - tags

70. M 2 (  ’ ) / cos   plot 1.0< M(K  )<1.4 GeV Our attempts to fit the M=4.43 GeV (cos   =0.25) peak with any combination of S-, P- & D-waves

71. M(DD): Broad threshold enhancement arXiv:0708.3812 Relativistic BW D sidebands D-reconstructed D-tag 3.8  Bg subtracted Resonance? Thresh effect? … ?

72. BaBar looked for a charged partner of the X(3872) and excluded isospin 1: BF(B 0  X - K + ) BF(X  J/ψ  -  0 ) < 5.4 x 10 -6 BF(B -  X - K 0 ) BF(X  J/ψ  -  0 ) < 2.2 x 10 -5 c.f BF(B 0  X 0 K+ ) BF(X 0  J/ψ  --  + ) =(1.28  0.41 ) x 10 -5

73. M(  ) near 4008 & 4260 MeV 3.8 < M(  J/  ) <4.2 GeV 4.2 < M(  J/  ) <4.4 GeV

74. Y(4660)  f 0 (980)  ’? 4.0 < M(  ’ ) <4.5 GeV4.5 < M(  ’ ) <4.9 GeV f 0 (980)?

75. K + K - J/  from Belle (very new) C.Z.Yuan et al (Belle) arXiv:0709.2565  (4415)? M=4875  132 MeV  = 630  126 MeV M=4430 +38 MeV  = 254 +55 MeV 4260 -43 -46

76. M(K + K - )