1. NTU colloquium June 11, 2007 S.L. Olsen U of Hawai’i 高能所 北京

2. X3872 X1835 Y4260 Stephen L. Olsen University of Hawai’I & 高能所 北京 Homeless mesons

3. Constituent Quark Model: 1964 (& 3 antiquarks) Mesons: qq p: u +2/3 p: u -2/3 +:+: d -1/3 u +2/3 d +1/3 u -2/3 d +1//3 u +2/3 -:-: u -2/3 d +1/3 s +1/3 u +2/3 d -1/3 s -1/3 Gell-Mann 3 quarks Zweig Baryons: qqq

4. Constituent Quark Model: 2007 (& 6 antiquarks) Mesons: qq c:c: c +2/3 c:c: u -2/3  + : s -1/3 s +1/3 d +1/3 c -2/3 u -2/3 b +1//3 u +2/3  - : b -1/3 u -2/3 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

5. but… quarks are not seen why only qqq and qq combinations? What about spin-statistics?

6. Fabulously successful at bringing order to the hadron “zoo” mesons baryons q q q q q

7.  s -1/3 three s-quarks in the same quantum state Das ist verboten!!

8. The strong interaction “charge” of each quark comes in 3 different varieties Y. Nambu O. Greenberg s -1/3 the 3 s -1/3 quarks in the  - have different color charges & evade Pauli --

9. QCD: Gauge theory for color charges generalization of QED    + i e A    + i  i G i QED gauge Xform QCD gauge Xform eight 3x3 SU(3) matrices 8 vector fields (gluons) 1 vector field (photon) scalar charge: e isotriplet charge: erebegerebeg QED QCD Yang Mills Nambu Fritzsch & GellMann

10. Attractive configurations  ijk e i e j e k i ≠ j ≠ k  ij e i ejej same as the rules for combining colors to get white : add 3 primary colors or add color+complementary color antiquarks:  anticolor charges Hence the name: Quantum Chromodynamics quarks: e i e j e k  color charges ejej eiei ekek

11. Difference between QED & QCD QED: photons have no charge QCD: gluons carry color charges gluons interact with each other  Coupling strengths distance

12. Test QCD with 3-jet events (& deep inelastic scattering) rate for 3-jet events should decrease with E cm gluon ss

13. “running”  s Why are these people smiling?

14. Running as tests QCD at short distances only  distance The long-distance regime, where the matter we are made of exists, remains untested.

15. Are there other color-singlet spectroscopies? Pentaquarks: e.g. an S=+1 baryon (only anti-s quark has S=+1) Glueballs: gluon-gluon color singlet states Multi-quark mesons: qq-gluon hybrid mesons uc u c cc u d u s d Non-quark model states expected in QCD

16. Pentaquarks “Seen” in many experiments BaBar CDF but not seen in just as many others High interest: 1 st pentaquark paper has ~720 citations Belle BES

17. Experimental situation is messy (some contradictory experiments) SAPHIR (2004) 4.8  M(nK + )(GeV) Counts/4 MeV nKKγp   s CLAS (2005) Same reaction

18. Some groups contradict themselves 5.2  CLAS-D (2003) no  signal CLAS-D (2005) ??? d+K-K+nd+K-K+n

19. Pentaquark Scoreboard Positive signals Negative results Also: Belle Compass L3 CLAS Yes: 17 No: 18

20. PDG 2006 “The conclusion that pentaquarks in general, and the   in particular, do not exist, appears compelling.” - George Trilling LBL

21. This is a risky business You never know if nature is smiling at you or something else

22. This talk: evidence for non-qq mesons cc uc u c 4 (& 6) quark states “hybrid” qq-gluon states

23. The Beijing Electron Positron Collider (BEPC) e+e+ e-e- 高能物理研究所

24. Beijing Spectrometer (BES)

25. e + e - annihilation cross section s c b E cm (GeV) q q BES Energy Range

26. J/    pp C -2//3 c +2/3 u +2/3 u -2/3 d -1/3 u +2/3 d +1/3 u -2/3 p p 

27. J/    pp This is the  c,  pp the J/  ’s spin=0 partner What is this??? M(pp) GeV

28. Fit the M(pp) distribution Best fit to this peak is a resonance with peak mass below the pp mass threshold M=1835 MeV no know  100MeV resonance

29. Actual fit M=1830.6 ± 6.7 MeV/c 2  < 153 MeV/c 2 (90% CL) J/    pp in the BES expt 00.10.20.3  2 /dof=56/56 fitted peak location

30. A pp bound state (baryonium)? p npp deuteron: loosely bound 3-q 3-q color singlets with M d = 2m p -  baryonium: loosely bound 3-q 3-q color singlets with M b = 2m p -  ? attractive nuclear force attractive force? There is lots & lots of literature about this possibility

31. An old idea

32. Fermi & Yang in 1949 (7 years before p discovery): If NN potential is attractive, they could bind to form  -like states.

33. Expectation for pp bound state meson m p +m p Above threshold X  pp ~100% below-threshold p and p annihilate to mesons I=0, J PC =0 -+ init. state: pp       ’ is common

34. Look in J/        ’ M(      ’) M=1833 MeV  70MeV m p +m p

35. X(1835): “6-quark” meson? u +2/3 u -2/3 d -1/3 u +2/3 d +1/3 u -2/3 3 quarks + 3 antiquarks Need to confirm J PC of the      ’ peak is 0 -+ Need to find it in other common 0 -+ pp annihilation channels

36. Move over to Japan Tsukuba Mountain KEK laboratory KEKB Collider

38. Belle Expt

39. e + e - annihilation cross section s c b E cm (GeV) q q KEK B-factory

40. Primer on Charmonium

41. B meson decays u -2/3 b -1/3 C -2/3 C +2/3 u -2/3 S -1/3 W-W- K-K- “Charmonium”

42. 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

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

44. “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

45. Charmonium spectrum All of these states are well established J/  ’’ cc c’c’  c   ’’ hchc

46. Study B  K -     J/  u -2/3 b -1/3 C -2/3 C +2/3 u -2/3 S -1/3 W-W- look here   J  KK

47. The X(3872) B  K     J/  M(  J  ) – M(J/  )  ’      J/  X(3872)      J/  S.K. Choi et al PRL 91, 262001

48. Its existence is well established seen in 4 experiments X(3872) CDF X(3872) D0 hep-ex/0406022 9.4  11.6 

49. Is it a cc meson? These states are already identified 3872 MeV Could it be one of these?

50. Determine J PC quantum numbers of the X(3872) with minimal assumptions

51. C=+1 is established X(3872)   J/  seen in: & Belle PRL 96 102002 M(  looks like a  X(3872)  ”  ”J/  seen CDF Belle hep-ex/0505037

52. Use Angular Correlations to determine J & P K  J/         e  e   J=0 X 3872 J z =0 z Rosner (PRD 70 094023) Bugg (PRD 71 016006) Suzuki, Pakvasa (PLB 579 67)

53. ll |cos  l  |  2 /dof = 34/9  |cos  | |cos  |  2 /dof=34/9 0 ++ 0 -+ rule out 0 ++ & 0 -+     J  k    x  J   Ruled out by Belle

54. Angular analysis from CDF CDF Collab. PRL 98, 132002 (2007) 1 ++ or 2 -+

55. Possible J PC values 0 -- exotic violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed (  (3S)) 1 -+ exotic DD allowed 1 ++ (  c1 ’ ) 1 +- (h c ’ ) 2 - - (  2 ) 2 - + (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 1 ++

56. can it be a 1 ++ cc state? 1 ++   c1 ’ (the only charmonium possibility) 3872  X      J/  decay is isospin-violating for a 1 ++ cc state (Isospin violating) M=3872 MeV is too low, especially now that we know that M(  c2 ’ )=3931  4 MeV The  (X   J/  ) partial width is expected to be 30~40 x  (X      J/  experimentally it is ~1/10th  Allowed E1 transition

57. Intriguing fact M X3872 =3871.2 ± 0.5 MeV m D0 + m D0* = 3871.6 ± 0.4 MeV lowest mass charmed meson lowest mass spin=1 charmed meson DD* 2 loosely bound qq color singlets with M = m D + m D* -   u c u c one  exchange attractive for 1 ++ Tornqvist PLB 590, 209 (2004) Braaten et al, PRL 93, 162001 Deuson? deuteron-like DD* bound state?

58. DeRujula, Georgi,Glashow, PRL 38, 317 (1977) X(3872)??

59. X(3872) = D 0 D* 0 bound state? J PC = 1 ++ is favored M ≈ m D0 + m D0* Large isospin violation is natural ( & was predicted) :  |D 0 D* 0 > = 1/  2 (|10> - |00>)  (X   J/  ) <  (X   J/  ) was predicted  (X  D 0 D 0  0 ) too large? Bf(B 0  K 0 X 3872 )/Bf(B +  K + X 3872 ) too large? Equal mixture of I=1 & I =0 Swanson PLB 598, 197 (2004) Tornqvist PLB 590, 209 (2004) Swanson PLB 588, 189 (2004) Braaten & Kusunoki PR D71, 074005 predict: < 0.08 BaBar measurement (hep-ex/0507090): 0.5  0.3

60. X(3872) summary –Existence well established –J PC = 1 ++ (probably) –Br(X      J/  ) too high for charmonium –Br(X  D 0 D 0  0 ) too high for molecule –Mass too low for hybrid Four years after discovery, theorists are still puzzling over what it may be

61. Next, California Stanford Linear Accelerator Ctr BaBar Detector

62. Radiative return s c b E cm (GeV) 10.58 GeV  B-factory energies 3~5 GeV

63. J/  sideband Well above DD & DD* threshold but wide & found in a suppressed mode?? M=4259  8 MeV  = 88  23 MeV B. Aubert et al. (BaBar) hep-ph/0506081 Y(4260) 10.58 GeV 4.26 GeV not seen in  (e + e -  hadrons) at Ecm =4.26 GeV J.Z. Bai et al. (BESII) PRL 88 101802 BES BaBar’s Y(4260)  (e + e -  hadrons)

64. No 1 -- cc slot for the Y(4260) 4260 X.H. Mo et al, hep-ex/0603024 J.Z. Bai et al. (BESII) PRL 88 101802 No place for it!

65. If not charmonium, what? cc “hybrid” cc-gluon state? But why does it decay to     J/ , and not to D and D* mesons?

66. Y(4260) summary – Existence well established – J PC = 1 -- –  (X      J/  ) too high for charmonium – Br(X  D ( * ) D ( * ) ) too low for hybrid Another mystery!!

67. Concluding remarks Pentaquarks are dead (at least for now) A number of “mysterious” mesons have been found Are these curiosities? or 1 st signs of new hadron spectroscopies? Hopefully, time, & more experimentation, will tell

68. 謝謝

69. Thank you

70. Back-up slides

71. Conclusion either: –The constituent quark model for mesons needs major revision or: –There is a new, non-qq, hadron spectroscopy, maybe more than one.

72. Difference between QED & QCD QED: photons have no charge QCD: gluons carry color charges gluons interact with each other

73. QCD: Gauge theory for color charges generalization of QED    + i e A    + i  i G i QED gauge Xform QCD gauge Xform eight 3x3 SU(3) matrices 8 vector fields (gluons) 1 vector field (photon) scalar charge: e isotriplet charge: erebegerebeg QED QCD Yang Mills Nambu Fritzsch & GellMann

74. Vacuum polarization QED vs QCD 2n f 11C A in QCD: C A =3, & this dominates

75. QED  QCD difference  Coupling strength distance

76. Test QCD with 3-jet events (& deep inelastic scattering) rate for 3-jet events should decrease with E cm gluon ss

77. “running”  s

78. 3872 quark-antiquark chalet No rooms left Fussy! x1835 Y4260 Looking for a home:

79. 3872 rats! Molecule Manors DD  x1835 Y4260

80. 3872 Hydrid heaven M<4.4 GeV need not apply Fat Cats! x1835 Y4260

81. Other hadronium states? M=1859 MeV/c 2  < 30 MeV/c 2 (90% CL) J/    pp in the BES expt M(pp)-2m p (GeV) 00.10.20.3 acceptance  2 /dof=56/56 fitted peak location +3 +5  10  25 J.Z.Bai PRL 91,022001(2003)

82. Charmonium state?  (e + e -  hadrons) No sign of it  (e + e -  hadrons) at Ecm =4.26 GeV BES 4260 J.Z. Bai et al. (BESII) PRL 88 101802 No place for it!

83. DD** threshold in relation to the “Y(4260)” 4.28-m D D** spectrum M(     J/  ) GeV No obvious distortions

84. it likes to decay to pp if it can Decays to mesons Decays to pp

85. A pp bound state (baryonium)? p npp deuteron: loosely bound 3-q 3-q color singlets with M d = 2m p -  baryonium: loosely bound 3-q 3-q color singlets with M b = 2m p -  ? attractive nuclear force attractive force? There is lots & lots of literature about this possibility E. Fermi, C.N. Yang, Phys. Rev. 76, 1739 (1949) Y.Nambu, G. Jona-Lasinio Phys Rev 122, 345 (1961) … I.S. Shapiro, Phys. Rept. 35, 129 (1978) C.B. Dover, M. Goldhaber, PRD 15, 1997 (1977) … A.Datta, P.J. O’Donnell, PLB 567, 273 (2003)] M.L. Yan et al., hep-ph/0405087 B. Loiseau et al., hep-ph/0411218 … These are very famous papers !!!

86. The X(3872) ???? Study     J/  produced in B  K     J/  decays

87. hadronic molecules a new spectroscopy? may be more particles to find

88. summary X(1835): – Existence well established – J PC = 0 -+ – Br(X  pp) too high for qq meson – X       ’ is expected for sub-thresh pp state