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Heavy Quarkonium Spectroscopy

Explore the fascinating world of heavy quarkonium spectroscopy, focusing on charmonium and bottomonium states. Learn about decay properties, production mechanisms, and the search for exotic quarkonium-like structures. This talk delves into the complexities of quantum numbers, decay modes, and experimental findings in quarkonium physics.

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Heavy Quarkonium Spectroscopy

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  1. Heavy Quarkonium Spectroscopy Riccardo Faccini University “La Sapienza” and INFN Rome Roma, 2 ottobre 2007 [tratto dal talk ad LP’07]

  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± BELLE-CONF-0773 • 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. Thresholds and new states  Molecular models and threshold effects require vicinity to threshold Is this the case? Y(4660) Z(4430)  Y(4350) Y(4260) X(4160) XYZ(3940)  X(3872)

  40. The observation matrix

  41. Comments & Perspectives • No systematic search on present B-Factory data • Groups working on this shrinking, should be revitalized • Also Tevatron has some homework (e.g. bottomonium spectroscopy) • Data involving D mesons have low stat (e.g. Br(Y(4260)DD)/Br(Y(4260)->J/ypp)<6.7 @95% C.L. – BaBar prelim) • 100 times the stat would help  SuperB or intermediate? • Hadron colliders have limited power: • cannot do all the needed final states • Limited capability at measuring JCP

  42. 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 (?) Rimbocchiamoci le maniche 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

  43. bakup

  44. 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

  45. CLEO and Belle on 4260

  46. 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.

  47. Below open charm threshold

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