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Heavy Quarkonium Spectroscopy

This presentation by Riccardo Faccini explores the realm of heavy quarkonium spectroscopy, focusing on charmonium and bottomonium. It covers fundamental concepts like bound states of quarks and antiquarks, quantum numbers, allowed JPC states, and decay properties. The discussion highlights the significance of understanding quantum chromodynamics (QCD) through observed states and the search for exotic forms such as hybrids and tetraquarks. Recent experimental results and theoretical insights on transitions and resonances are also presented, providing a comprehensive overview of advancements in the field.

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Heavy Quarkonium Spectroscopy

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  1. Heavy Quarkonium Spectroscopy Riccardo Faccini University “La Sapienza” and INFN Rome Lepton Photon 2007 13-18 August Daegu, Korea

  2. Only charmonium and bottomonium considered here Quarkonium for Pedestrians • Quarkonium is a bound state of a quark and an antiquark • Relevant quantum numbers: n,L,S,J • Relationship with Parity and Charge Conj: • P=(-1)L+1, C=(-1)L+S • Not all JPC allowed (e.g. 0+-,0--,1-+,2+- forbidden) • Decay Properties: • Below open quark threshold (e.g. (cc)DD) only electromagnetic or as suppressed decays allowed  mostly narrow states • Above open quark threshold (if DD decays allowed) mostly broad states • What can we learn? • Understanding of QCD: • ‘regular quarkonium’  tests of NRQCD, potential models, … • ‘new states’  new forms of aggregations mediated by the strong interactions

  3. Charmonium: state of the art same JPC as J/y but mostly D wave ! (2S+1)LJ y(4160) Increasing L  M(MeV) y(4040) Open charm thr. y(3770) Increasing n  h’c y’ cc2 hc cc1 cc0 Recent acquisitions J/y hc (pot. Models) QWG: hep-ph/0412158 JPC Basically all states below the open charm threshold are observed and explained

  4. Bottomonium: state of the art hb (x3) completely missing 2 hb and 3 D wave states are narrow but not observed Open bottom thr. Increasing L  Y(3S) c(2P)b{2,1,0} Y(1D) Y(2S) Increasing n  c(1P)b{2,1,0} Unconfirmed J assignments of all the cb s Y(1S) (pot. Models) QWG: hep-ph/0412158 8 narrow resonances still missing !

  5. Beyond the quarkonium • Search for states with 2 quarks+”something else” • New forms of aggregation • Expected but never identified!!! • Hybrids: qq+n gluons • Lowest state 1-+ (forbidden for quarkonium) • Dominant decay HDD** • Tetraquarks: [qq’][qq’] • Large amount of states • small widths also above threshold • Molecules: M[qq]M[q’q’] • Smaller number of states but still small widths also above threshold • Search for resonances: • with non-quarkonium JPC • unnaturally small widths • not null charge: would be clear indication of something new going on

  6. Measuring the quantum numbers gISR e+ X • Production: • ISR only produces with same quantum numbers as the photon (JPC=1--) • gg only produces with C=+ • Double charmonium production e+e- g*Xcc1Xcc2 Possible only if quantum numbers of the two charmonia can be combined to give a 1--. • Decay: • Angular distributions of decay products depend on JP. • Selection rules • Conservation of J • Conservation of P,C in strong and e.m. decays e- e+ e+ X e- e-

  7. Samples used in results Experiments 58MJ/y, 14M y(2S) • e+e-Charmonium (CLEO-c, BES-II) • L~1033/cm2/s • E=3.0-4.3 GeV • e+e- Y(4S): (BaBar, Belle, CLEO) • L~1034/cm2/s • Charmonium in B decays, ISR and gg production • Capability to measure JPC also in production • pp colliders (CDF, D0) • High Xsection  copious production • Extremely high backgrounds 3M y(2S), 1.8 M y(3770) 1.5M Y(1S),1.9M Y(2S), 1.7M Y(3S),9M Y(4S) 657M Y(4S) 383M Y(4S) 1.3 fb-1 800pb-1 • Disclamers: • time is very short •  could not cover everything • theory statements are indicative

  8. Quarkonium Spectroscopy

  9. DD*2(2460) DD not DD*2(2460) Updates on 1-- charmonium states NEW arXiv:0705.4500 Belle-CONF-0771 NEW ~14σ improved measurements, including interference for the first time!!! First exclusive decay observed: DD*2(2460) [dominant]  3D1 candidate • CLEO-c observes y(3770)cc0g • Confirms 3Dassignment [hep-ex/0605070]

  10. Y(nS)Y(mS) transitions The issue: • Quarkonium transitions between 3S1 states described by the QCD Multipole Expansion • Tests heavy quark and low energy hadronic systems • BR(X(nS)X(mS)h)/ BR(X(nS)X(mS)pp) • pp invariant mass spectra  simplest PCAC matrix element expects enhancement at high masses • Data on Charmonium transitions well fitted by predictions • Bottomonium physics richer because of larger phase-space • Y(2S) and Y(3S) transitions known for years • Y(4S) transitions (above open beauty threshold) much more difficult [high backgrounds]  only recent results

  11. Y(4S)  Y(nS)pp PRL 96,232001(2006) Phys.Rev.D75:071103,2007 Y(4S)Y(1S)pp Y(4S)Y(2S)pp As predicted by simplest PCAC matrix elements Low mass structure to be understood!!

  12. NEW Y(3S)  Y(nS)pp • From CLEO’s run @ Y(3S) [5x106 Y(3S)] • Fit to the Multipole Expansion parameters • Results consistent with no ‘C’ term Breaking of the expansion The Multipole Expansion model fits the data (but not in its ‘naivest’ form) arXiv:0706.2317

  13. Y(2S)Y(1S) h,p0 • Rates predicted by QCD ME BF(Y(2S)hY(1S))=(8.1±0.6)10-4 [Kuang hep-ph/0601044] • Direct search from CLEO  5s evidence Egg-mgg (MeV) BF(Y(2S)hY(1S)) = (2.5±0.7±0.5)10-4 BF(Y(2S)p0Y(1S)) < 2.1 10-4

  14. Quarkonium polarizations QCD predicts high pT S-wave quarkonium to be transversely polarized in pp collisions. • Recent updates on J&y(2S) (CDF) and Y(nS) (D0): arXiv:0704.0638 Y(1S) NRQCD CDF PRL88,161802 (2002) J/y 800 pb-1 Clear violation of NRQCD for J/y, y(2S), Y(1S) [Y(2S) follows NRQCD]

  15. BhcK*,hc K(*) NEW • Very little known about dynamics involving hc. • NRQCD predicts Br(BccJK(*))~Br(BhcK(*))~10-4 • recent measurements: Br(B0hcK*0)=(6.1±0.8±1.1)10-4 Br(B+hcK+)x Br(hchcg) <5.2 10-5 Br(B0hcK*0) x Br(hchcg) <2.4 10-4 • Suppression in hc production [or low Br(hc hcg)] arxiv:0707.2843

  16. The new zoology X(3872) The 1-- family Y(4260) The 3940 family X(3940) breaking news

  17. X(3872): known facts • Decays • XJ/y pp (original observation) • Maybe J/y r • BF(XJ/y w)~ BF(XJ/y r) • XJ/y g Implications: • C(X)=+1 • C(pp in J/y pp decay)=-1 • I(pp)=L(pp)=1  consistent with J/yr decay hyp. • Production • only B decays so far • No prompt e+e- production observed (BaBar arXiv:0707.1633) Belle+BaBar NEW

  18. Analysis of JPC of X(3872) PRL 98:132002 (2007) Full angular analysis of XJ/ypp decays Only compatible options: JPC=1++ or 2-+ (and with J(pp)=1) 1++ 2-+ Belle (hep-ex/0505038) disfavours P=-  JPC=1++ 1-- 0++

  19. The X(3872) puzzle Not matching any predicted state! Above DD threshold (allowed): should have large width but it is narrow Charmonium highly suppressed decay into J/y r (isospin violation) y(4160) (2S+1)LJ Increasing L  M(MeV) Open options • DD* molecule • Right above the threshold • favours DD* decay over J/ypp over J/yg (as observed) • Tetraquark • Explains small width • Predicts a set of 4 states (2 charged and 2 neutral). • Finding the charged state is critical y(4040) X(3872)? Open charm thr. y(3770) Increasing n  h’c y’ cc2 hc cc1 cc0 J/y (pot. Models) hc JPC More from theorists…

  20. X(3872)D0D*0 NEW BABAR-PUB-07/049 B+ & B0 D0D*0K • Belle [PRL 97, 162002 (2006)] observed X(3872)D0D0p0 • Confirmation and integration from BaBar in BDD*K Hints of X in neutral B decays Mass and BR measurement Warning! very low significance N.B.

  21. X(3872): G and angular analysis Dc2 1- JP=1+ 2- 2+ cos(Helicity angle) First angular analysis (still low stat) First info on G (≠0 @ 1.3 s) NEW BABAR-PUB-07/049

  22. X(3872): update on J/ypp NEW Belle-CONF-0711 Update mass and BF in BXK, XJ/y pp 6.5s (first obs.) B0XKS B±XK± Consistent with: no mass difference no rate difference Prior results: BaBar PRD73, 011101 (2006)

  23. X(3872) mass NEW [my extrapolation] Poor agreement among mass measurements: XJ/ypp and XDD(*) differ by ~4s Neutral and charged B mesons in XJ/ypp by 1.5s NEW DD average J/ypp average Predicted by tetraquark model (but why so close to threshold?) TWO STATES? X(3872) & X(3876) ?

  24. The new zoology X(3872) The 1-- family The 3940 family breaking news

  25. The 1-- family Several resonances observed in e+e- YgISR(certainly JPC=1--) Y(4260)J/ypp Confirmation + J/yp0p0: CLEO PRD74, 091104 (2006) CLEO-c PRL 96, 162003 (2006) A new state: Y(4260) PRL 95, 142001 (2005) Yet another state Y(4350) PRL 98, 212001 (2007) Y(4350)y(2S)pp

  26. The youngest of the 1-- family arXiv:0707.3699 arXiv:0707.2541 Confirmation of BaBar 5.8s NEW NEW NEW Zoomed BaBar YJ/ypp Yy(2S)pp

  27. Y(4008) Y(4260) High mass region Decay properties DECAY PROPERTIES NEW f0 dominating? Threshold effects? Y(4660) Y(4350)

  28. [Belle: arXiv:07080082] hep-ex/0607083 D(*)D(*) in ISR DD Most of these 1-- states should preferentially decay into D(*)D(*) states. Can we see them? y(3770), y(4040), y(4415) [regular charmonia] clearly visible, nothing else PRL 98, 092001 (2007) D*D*  Basically all R scan other than non-resonant continuum understood DD* Xsection (pb) DDπ,not D(2010,2007) arXiv:07080082 S [D(*)D(*)(p)] continuum

  29. J/y KK in ISR • Knowledge of the strangeness content of these resonances is critical to disentangle their nature • CLEO-c already showed few e+e- Y(4260)J/y K+K- • Belle (ISR): first observation of e+e- J/y K+K- and J/y KsKs e+e-  J/y K+K- e+e-  J/y KSKS CLEO-c @4260 s(e+e-J/yKsKs)/ s(e+e-J/yK+K-)=0.6+0.5-0.4 Consistent with isospin (0.5) BELLE-CONF-0772

  30. 1-- family: recap Only seen in y(2S)pp (2S+1)LJ • Not matching any potential model prediction • Too narrow 4660 M(MeV) 4350 y(4160) 4260 4008 y(4040) 4 Ys to place ! Open charm thr. y(3770) y’ “new physics”? 4260 can be fit by a tetraquark model (decaying into J/yf0 …) or a hybrid (with gpp) J/y Why not the ordinary Y(4040)? (pot. Models) JPC 1-- 1--

  31. The new zoology X(3872) The 1-- family The 3940 family breaking news

  32. The 3940 family PRL 98, 082001 (2007) PRL 94, 182002 (2005) PRL 96, 082003 (2006) YJ/yw ZDD XDD*

  33. G. Cibinetto, talk at this conference Confirmation of Y(3940) (BKwJ/y) p+p-p0 BYK preliminary • New result, based on 350 fb-1: • Belle’s evidence for BYK, YJ/ confirmed • ~30MeV lower mass than Belle’s • Narrower width • Clear demonstration of decay into w • Preliminary BF estimate similar to Belle’s (~10-5) B0YKS B0/B Y(3940) closer to X(3940) Can they be the same state? Isospincons. M(J/y w) (GeV)

  34. “Just” charmonium states? (2S+1)LJ • Poor match with predictions • Above threshold? • If X≠Y, difficult to explain absence of Yopen charm • Hybrid? M(MeV) X,Y X Z Open charm thr. y(3770) h’c cc0 cc1 cc2 hc (pot. Models) JPC

  35. The new zoology X(3872) The 1-- family The 3940 family breaking news!!

  36. Obtain J/yD(*)D(*)samples through kinematic separation, look at m(D(*)D(*))after background subtraction: X(4160) D*D* e+ e-J/y D(*)D(*) BELLE-CONF-0705 M = 3942 ±6 MeV tot =37 ±12 MeV Nev= 52 ±11 reconstructed Inferred (Recoil mass) Something’s here, but it’s not X(3940) 3.8  X(3940) is still there, 6.0s J/y D+ D* D*D* D Number of events M(DD) M(DD*) X(4160) claim: new state 5.5  J/y D*+ X(3940) Cross-check D* D M(D*D) M(D*D*) M = 4156 ±15MeV tot = 37 ±21MeV Nev= 24 +25 - 20 +111 - 61 One more particle to explain … JCP=0-+ not excluded (hc(3S)) +12 - 8

  37. The first charged state: Z(4430)! B±Z±Ks or B0ZK± Z±y(2S)p± arXiv:0708.1790 • Total significance: 7.3s • M = (4433±4) MeV • = (44+17-13) MeV BF(BKZ)xBF(Zy(2S)p)=(4.1±1.0±1.3) 10-5 Too narrow to be a reflection Xcheck: separate in subsamples BF and mass consistent between B± and B0 within large errors [in B± decays M=(4430±9) MeV ; BF±/BF0=1.0±0.4 ] Prior search with no evidence: BX+K with X+J/y pp0 PRD 71, 031501 (2005)

  38. Summary Updated properties The 1-- family: Charmonia, tetraquarks, molecules, hybrids?!? (2S+1)LJ Z(4430): the first charged state M(MeV) y(4415) y(4160) X,Y News on the 3940 family X(3872) the best tetraquark candidate y(4040) X Z Open charm thr. y(3770) h’c y’ cc2 hc cc1 cc0 Yet another particle: X(4160) [hc(3S)?] J/y (pot. Models) hc JPC + updates on Y(nS)Y(mS) transitions

  39. Summary Updated properties The 1-- family: Charmonia, tetraquarks, molecules, hybrids?!? The discovery and identification of a new spectroscopy seems close (2S+1)LJ Z(4430): the first charged state M(MeV) y(4415) y(4160) X,Y WHAT A MESS !!!! ( of data) News on the 3940 family X(3872) the best tetraquark candidate (?) y(4040) X Z Open charm thr. y(3770) h’c y’ cc2 hc cc1 cc0 Yet another particle: X(4160) [hc(3S)?] J/y (pot. Models) hc JPC + updates on Y(nS)Y(mS) transitions

  40. Summary Updated properties The 1-- family: Charmonia, tetraquarks, molecules, hybrids?!? The discovery and identification of a new spectroscopy seems close (2S+1)LJ Z(4430): the first charged state M(MeV) y(4415) y(4160) X,Y WHAT A MESS !!!! ( of data) News on the 3940 family X(3872) the best tetraquark candidate (?) y(4040) X Z Open charm thr. y(3770) h’c y’ cc2 hc cc1 cc0 Yet another particle: X(4160) [hc(3S)?] J/y (pot. Models) hc JPC + updates on Y(nS)Y(mS) transitions

  41. bakup

  42. Fits to J/y KK invariant mass ‘Standard ‘ y(4415) + 1 BW: M = (4875±132) MeV G = (630±126) MeV single BW: M = (4430±38) MeV G = (254±49) MeV

  43. Thresholds and new states Y(4660) Y(4350) Y(4260) X(4160) XYZ(3940) X(3872)

  44. CLEO and Belle on 4260

  45. Search for X(3872)J/yg in continuum 386fb-1 arXiv:0707.1633 J/ production observed in continuum while no evidence of c states. cc1 X(3872) c1,2 or X(3872) cc2 X>2 ch c production is consistent with the expected contributions from prompty(2S) production feed-down tocc: no evidence of prompt c1,2 No evidence of X(3872) production in e+e- annihilation.

  46. Below open charm threshold

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