1. Searching for new forms of hadronic matter Stephen L. Olsen University of Hawai’i & 高能物理所 北京 Wuhan 武汉 10/15/07

2. History: ( sub-atomic particles) 1932: proton & neutron..all we need??? 1937: muon “Who ordered that?” 1947: pion predicted in 1935 1950’s: , , , , ,… “Had I foreseen that, I would have gone into botany” – Fermi chadwick Fermi TingPetersJones Rabi Yukawa Joliet-Curie

3. Hadron “zoo” mesons baryons No “economy”

4. 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 -:-: d -1/3 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

5. Constituent Quark Model: 2007 (& 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

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

7. Fabulously successful, but… Why are isolated quarks are not seen? why only qqq and qq combinations? What about spin-statistics?

8.  s -1/3 three s-quarks in the same quantum state 禁止

9. The “charge” for the strong force is a 3-dim spinor Y. Nambu O. Greenberg s -1/3 the 3 s -1/3 quarks in the  - have different color charges & evade Pauli -- Each quark can have 3 different “color” charges

10. 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 triplet charge: erebegerebeg QED QCD Yang Mills Nambu Fritzsch & GellMann

11. 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

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

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

14. “running”  s Winners of the 2004 Nobel Prize

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

16. Are there other color-singlet arrangements? 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

17. Spring8 electron Ring in Japan

18. A pentaquark? T.Nakano et al (LEPS) PRL 91 012002 (2003)  742 citations!!  + (1530)? M(K + n) s +1//3 u +2/3 d -1/3 S=+1 baryon: impossible with only qqq  + n  K - K + n

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

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

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

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

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

24. Another approach: look for non-qq mesons cc uc u c 4 (& 6) quark states “hybrid” qq-gluon states u u u u d d theory: mc 2 >4.2 GeV

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

26. Beijing Spectrometer (BES)

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

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

29. J/    pp This is the  c  pp the J/  ’s well known S=0 partner What is this??? M(pp) GeV BESII J.Z. Bai et al. (BESII) PRL 91 022001 (2003)

30. Fit the M(pp) distribution Best fit to this peak is a resonance with peak mass below the pp mass threshold M=1830.6 ± 6.7 MeV/c 2  < 153 MeV/c 2 (90% CL) matches to no known state.

31. 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

32. An old idea

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

34. 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 Ding & Yan Phys.Rev.C72:015208,2005.

35. BES looked at J/        ’ M(      ’) M=1833 MeV  70MeV m p +m p These values match those for the pp peak (as predicted by Ding&Yan) BESII M. Ablikim et al. (BESII) PRL 95, 262001 (2005)

36. X(1835): a“6-quark” meson? 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 job for BESIII u u u u d d

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

39. International Collaboration Belle

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

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. Primer on Charmonium

43. 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

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

45. “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

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

47. 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

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

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

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

51. The J PC quantum numbers of the X(3872) are 1 ++ From studying different decay processes & angular correlations among decay products

52. can it be the 1 ++ cc state? 1 ++   c1 ’ (the only charmonium possibility) 3872  X      J/  decay is a forbidden decay (Isospin violating) M=3872 MeV is low,  Allowed E1 transition 2 3 P 1 cc state

53. 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?

54. Another old idea DeRujula, Georgi,Glashow, PRL 38, 317 (1977) X(3872)??

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

56. Next, California Stanford Linear Accelerator Ctr BaBar Detector

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

58. 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) PRL 95 142001 (2005) 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 Y(4260)  (e + e -  hadrons)

59. a 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 cc slot for it!

60. Theorist’s favorite interpretation cc “hybrid” qq-gluon states just about the right mass for theory

61. A      ’ 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 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)

62. New results on the      ’ peak from Belle 548 fb -1 X.L. Wang et al (Belle) arXiv:0707.3699 It is really two peaks! M=4664  11 ± 5 MeV  = 48  15 ± 3 MeV M=4361  9 ± 9 MeV  = 74  15 ± 10 MeV (both relatively narrow) (neither one consistent with 4260) 4260

63. Need 2 more 1 -- cc slots for Y(4630) & Y(4660) 4260 X.H. Mo et al, hep-ex/0603024 4660 4360 Excited hybrid states? cc

64. Latest News electrically charged!!

65. M(  ±  ’) from B  K  ±  ’ K. Abe et al (Belle) arXiv:0708.1790 M(  ’ ) GeV 6.5  M = 4433 ± 4 ±1 MeV  tot = 45 +17 +30 MeV Nsig =124 ± 31evts -13-11

66. Can’t be a cc meson or a hybrid 4260 4660 4360 No charged cc hybrid states gluons have zero charge C +2/3 C -2/3

67. Summary Mesons with no qq assignment: M(pp) GeV X(1835) M(  J  ) – M(J/  ) X(3872)      J/  Y(4260) 548 fb -1 Y(4660) Y(4360) M(  J  ) M(  ’ ) GeV Z ± ( 4430) Y(3940) M(  J/  ) MeV BESII

68. Concluding remarks A number of “mysterious” mesons that don’t fit into the simple quark model picture have been found If they are related to each other, these particles can’t be the hybrid states predicted by QCD Are these curiosities, each with its own story? … or are they 1 st signs of a spectroscopy of new forms of hadronic matter? Hopefully, time, & more experimentation, will tell

69. 謝謝

70. Thank you

71. Back-up slides

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

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

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

75. The LEPS observation of  + (1530) n  K-K- n K+K+  + n  K - K + n M(K + n) s +1//3 u +2/3 d -1/3   (1530) Physical Review Letters, 91, 012002 (2003)  + n  K -  +  K - K + n S=+1

76. 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!

77. 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

78. 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 !!!

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

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

81. 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

82. 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

83. 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

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

85. 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)

86. 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 ++

87. 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

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

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

90. 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!!

91. 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 