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Quarkonia spectroscopy at CDF

Quarkonia spectroscopy at CDF. Heavy Quarkonia 2006. Ulrich Kerzel, University of Karlsruhe for the CDF collaboration. Content: X(3872) m(  +  - ) mass spectrum quantum numbers J PC search for  b. Heavy quark physics at the Tevatron. huge inelastic cross-section:

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Quarkonia spectroscopy at CDF

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  1. Quarkonia spectroscopy at CDF Heavy Quarkonia 2006 Ulrich Kerzel, University of Karlsruhe for the CDF collaboration • Content: • X(3872) • m(+-) mass spectrum • quantum numbers JPC • search for b

  2. Heavy quark physics at the Tevatron • huge inelastic cross-section: • ¼ 5000 times bigger than for • )triggers are essential! • events “polluted” by fragmentation tracks, underlying event, pile-up • ) need precise tracking and good resolution • dedicated trigger for • J/!+-: m(+-) around m(J/) • ) high quality J/ events with large statistics(channel J/! e+e- much more challenging in hadronic environment) • lepton + track with large IP (semi-leptonic B decay) • two tracks with large IP (hadronic B decay) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  3. The X(3872) • discovered 2003 by Belle in search for charmonium states • m(+-) spectrum compatible with 0 • CDF PRL 96,102002 (2006) • mass: m = 3871.3 § 0.7 § 0.4 MeV/c2 • CDF PRL 93,072001 (2004) , • width compatible with detector resolution •  < 2.3 MeV/c2Belle PRL 91,26001 (2003) • No X++ or X– --CDF PRL 93,072001 (2004) • No iso-partner X§BaBar PRD 71, 031501 (2005) • Evidence for X ! J/ , J/  • Belle hep-ex/0505037 (2S) ! J/ +- known resonance • ) what is the X(3872)? charmonium? exotic? • ! determine quantum numbers JPC • m(+-) sensitive to JPC • use distribution of angles between decay particles to measure JPC U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  4. m(+-) mass spectrum for (2S) • (2S) in same exclusive final state • m(+-) spectrum known: • s-wave with small • d-wave contribution • e.g. model by • Novikov-Shifman ) high precision data by CDF ) allows to discriminate between models U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  5. The m(+-) mass spectrum Mass spectrum sensitive to JPC if (+-) in s-wave state: shape needs to be modelled e.g. multipole expansions for if (+-) in p-wave state: shape follows Breit-Wigner e.g. decay via 0!+- • m(+-) favours high end of mass spectrum • )compatible with intermediate 0!+- resonance • also 3S1 multipole-expansion for charmonium possible • no charmonium candidate at that mass • 3S1 also has JPC = 1-- ) non-observation by BES • ((e+e-)B(+-J/) < 10 eV @90% C.L. ) notation: n2s+1LJ (JPC) Phys.Lett.B579:74-78 (2004) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  6. The m(+-) mass spectrum • for broad resonances (0): • kinematic quantities vary across width • introduce form-factor • e.g. Blatt-Weisskopf • depends on ang. momentum L, • effective range R • ) affects shape for L=0, L=1 • Possible 0 -  mixing: •  mass contribution far from pole position • interference 0$ possible )L=0 and L=1 both compatible with m(+-) spectrum )mixing phase of 95± describes data U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  7. Determination of JPC (1) definition of angular variables: example: JPC assumptions U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  8. Determination of JPC (2) • Predictions for kinematic decay quantities fromhelicity formalism: • )decay chain as sequential 2-body decays • X(3872) ! J/ (+-)s,p !+-+- • need: • one matrix element per decay vertex • propagators to connect vertices • matrix elements: angular part A and kinetic part T • assume state with lowest L dominates, neglect others • dedicated simulation for each JPC hypothesis • (including detector effects) • compare to angular distributions measured in data via 2 U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  9. Determination of JPC (3) • Limitations from helicity formalism: • no model-independent description of +- in s-wave • Breit-Wigner for 0!+- depends on form-factor details • ) fix m distribution to match the data • )analyse angular distributions only • N.B. 0 and  have both JPC = 1- - • ) angular distributions not affected by potential interference • JPC = 1-+ and 2-+: multiple sub-states with same L contribute • ) Can an arbitrary mixture describe the data? U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  10. Result for (2S) obtain expected result: JPC = 1- - • Exploit correlations between angles via 3D fit: • 3 bins in  • 2 bins in J/ • 2 bins in  U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  11. Result for X(3872) Only JPC = 1++ or 2-+ compatible with data! All other tested hypotheses excluded by > 3 U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  12. What is the X(3872) ?? • Charmonium ? potential candidates: but: • decay via 0: isospin violating • mass predictions from potential models ¼ 50-100 MeV/c2 off • exotic? • m(X) ¼ m(D0) + m(D0*) ! coincidence? • charmed molecule ? ( or or ...) • hybrid state, i.e. ? (but expected above ¼ 4 GeV/c2) • mainly charmonium - but interaction with ? notation: 2s+1LJ (JPC) e.g. M. Suzuki hep-ph/0508258 U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  13. X(3872) with neural networks • Use sophisticated neural networks for • “next generation” X(3872) analyses: • exploit correlations between variables • ! improved candidate selection • train networks for multiple • JPC assignments • further handle to test hypotheses: • “good” hypotheses • ! higher significance • to be used in likelihood analyses • strong suppression of combinatorial BG • ! to be used in search for • partner of X(3872) in B system: U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  14. Search for b (1) • ground state of system • test NRQCD: • ~30-160 MeV/c2 lighter than • not yet observed, searches: • LEP !b • CLEO • 2 evidence from CDF RunI • search in exclusive final state: • b! J/  J/  !+-+- • JPC: 0-+! 1- - 1- - • BR(!) ¼ 40% • BR(c!) ¼ 3¢ 10-3 • expect BR ¼ 7¢ 10-5 – 7¢ 10-3 Phys. Rev. D 63, 094006 (2001) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  15. Search for b (2) • use 1.1 fb-1 data from J/!+- trigger • candidate selection: • b! J/ J/ • 2 of vertex fit < 18.5 • || < 0.6 • pt (b) > 3 GeV/c • J/ (1): J/ ! +- trigger • || < 0.6 • pt (J/ ) > 3 GeV/c • pt (§) > 2.0 GeV/c • J/ (2):  + track • pt(J/) > 3 GeV/c • pt(§) > 2 GeV/c (||<0.6) or • > 3.5GeV/c (0.6 < || < 1.0) • pt(track) > 1.5 GeV/c • dE/dx residual < 3.7 • (track) pt(J/) > 50 GeV/c U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  16. Search for b (3) • after cuts: • 3 candidates observed in 9.0 – 9.5 GeV/c2, • expect 3.6 background events • ) no significant evidence of b • ) upper limit on b production cross-section U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  17. Conclusions & Outlook • Tevatron and CDF performing well, rich B physics programme • New results on X(3872): • 3D angular analysis: JPC = 1++ or 2-+ • m(+-): • both L=0 or L=1 transition via 0 compatible with data ) cannot exclude J-+ hypotheses from m(+-) • possibly 0$ interference with =95± ) both charmonium and exotic interpretation still “in the game” • further analyses using neural networks started • ongoing search for in molecular picture: expect further states similar to X(3872), e.g. • Search for b! J/ J/: • no signal observed, upper limit on production cross section U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  18. BACKUP U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  19. Tevatron Run 2 • 1 fb-1 delivered June 2005 • ¼ 15-20 pb-1/week delivered before spring 2006 shutdown 1 fb-1 delivered • analyses presented use ¼ 0.3 – 1.0 fb-1 • (“good data”) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  20. The Tevatron CDF D0 Tevatron RunI: 1992 – 1996 data taking period at RunII: 2001 – 2009 major upgrades to collider and detectors Main injector and recycler U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  21. Tevatron performance 1 fb-1 Running well - both peak luminosity and integrated luminosity before spring 2006 shutdown: ~15-20 pb-1 / week delivered 1 fb-1 delivered in beginning of June 2005 . U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  22. The CDF detector • precise tracking: silicon vertex detector and drift chamber • important for B physics: direct trigger for displaced vertices, J/ !+- U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  23. Physics at the Tevatron • large b production rates: • ) 103 times bigger than ! • spectrum quickly falling with pt • Heavy and excited states not produced at B factories: • enormous inelastic cross-section: • ) triggers are essential • events “polluted” by fragmentation tracks, underlying events • ) need precise tracking and good resolution! U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  24. Dedicated trigger J/!+- Evaluate muon chamber info on trigger level: • trigger events where m(-)around m(J/ ) • high quality J/  events • large statistics available N.B. channel J/ ! e+e- much more challenging in complex hadronic environment! U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  25. X(3872) with J/! e+ e- Reconstruction of J/! e+e- very difficult in complex hadronic environment strong radiative tail • dedicated J/! e+e- trigger • use neural-network based approach to identify soft e§ (pt > 2GeV/c) • reject e§ from conversions based on neural network approach • add  at J/ vertex to accommodate Bremsstrahlung • X(3872) reconstructions follows • J/!+- case ) able to reconstruct X(3872) in this channel! U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  26. X(3872) production fraction from B fraction from B decays: (2S): 28.3 §1.0 (stat.) § 0.7 (syst.) % X(3872): 16.1 § 4.9 (stat.) § 1.0 (syst.)% ) X(3872) behaves similarly to the (2S) (with given uncertainties) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  27. The m(+-) mass spectrum • Distribution of m(+-) constrains quantum numbers JPC • shape depends on: • decay of (+-) sub-system: (+-) in s or p wave • (i.e. intermediate sub-resonance or not) • relative angular momentum between (+-) and (+-) • (and detector acceptance, efficiency, etc.) e.g. for decay chain: X ! J/0; 0!+- spectrum described by Breit – Wigner function for broad resonances (kinematic factors vary across width) form-factor U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  28. The m(+-) mass spectrum • Challenge: Large background, rather low X(3872) yield • ) sideband-subtraction difficult, instead: • “slicing technique” • impose bin borders in m(+-) as additional cuts • fit resulting (+-+-) mass spectrum • obtained yield shows variation with m(+-) need to be careful at kinematic borders U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  29. Influence of form-factor on m(+-) use: model from Blatt-Weiskopf: parameter “R” determines effective size, no unique choice U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  30. Mixing phase between  and  good fit probability found for relative phase ¼ 95± Relatively small influence of 0 form-factor radius, large effect from X(3872) form-factor radius. U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  31. Effect of 0-  mixing )Neither L=0 nor L=1 can be ruled out from m(+-) alone U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  32. Illustration of angular correlation example for JPC = 1++ U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  33. Sample fit for X(3872) angular analysis U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  34. Helicity matrix element • treat initial and final state in respective rest-frame • two body decay: • are back-to-back • common quantisation axis • )final state helicity  = 1 - 2 using Wigner D functions assume lowest angular momentum L is dominant U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  35. Transition weight from Helicity matrix element incoherent sum over final states coherent sum over intermediate states mean over initial state in case of several substates: coherent sum contains a priori unknown mixing constant gLS U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  36. X(3872) fit results U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  37. Systematics for X(3872) systematics: 13 – 17: details of MC 12: use phase-space to describe m() 10, 11: vary 0 form-factor radius 6-9: vary X(3872) mean and width 4,5: vary histogram bin width 2,3: vary X(3872) fit window 1: default result U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  38. (2S) fit results U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  39. Systematics for (2S) systematics: 13 – 17: details of MC 6,7 : vary (2S) mean and width 4,5: vary histogram bin width 2,3: vary (2S) fit window 1: default result U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  40.  for JPC = 1-- Detector effects Detector acceptance, resolution and cuts affect angular variables: original after simulation  for JPC = 1++ left: 1++ right: 1-- U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  41. 0 Charmed molecule? e.g. DeRujula, Georgi, Glashow (1977) ? possible formation of “molecules”: decay via: binding by 0 TörnqvistPhys. Lett. B590, 209-215 (2004) SwansonPhys. Lett. B588, 189-195 (2004) similar to deuteron: small attractive force mediated by 0 predict JPC = 1++ or 0-+ isospin breaking via 0!+- allowed Swanson: additional contribution from , 0, only JPC = 1++ U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  42. 0 „Deuson“ model (Törnqvist) • X(3872) similar to deuteron: • composed of two objects • bound by 0 exchange • Prediction: • JPC = 1++ or 0-+ • (otherwise potential too weak or repulsive) • small binding energy: • narrow resonance, big object • isospin breaking: • X! J/0, 0!+- allowed • X! J/forbidden for any isoscalar  • X! J/ 00 forbidden U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  43. Further properties by B-factories (hep-ex/0408083) • BaBar: • search for charged partner X§! J/§ • expect twice the rate if X is part of iso-triplett ) no signal found • Belle: • 4  evidence for decay X(3872) ! J/ • evidence for decay X! J/+-0 )Swanson: 1++ has contribution of X ! J/, ! +-0 • search for X!c1, X!c2 ) no signal found C = +1 (hep-ex/0505037) (hep-ph/0311229) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  44. Excited B mesons narrow: ~ 10 MeV/c2 broad : ~ 100 MeV/c2 similar picture for Bs** Heavy Quark Effective Theory: hydrogen atom like system with heavy + light quark U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  45. Exclusive Bd** experimental observable: Q = m(B**) – m(B) – m() (free remaining kinetic energy) • focus on narrow states: • B1! B* • B2*! B  • B2*! B* • ( not reconstructed) • exclusive analysis • ) high resolution U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  46. Exclusive B** HQET: hydrogen atom like system with heavy + light quark • focus on narrow states: • B1 , B2*! B* • B2*! B  • Towards Bs¤¤: • similar to Bd¤¤: Bs¤¤! B§ K¨ • situation much less clear: • signal so far from DELPHI, OPAL, D0 • exclusive B§! J/ K§ , B§! D § • sophisticated neural networks to suppress background • expect result ~summer observable:Q = m(B**) – m(B) – m(/K) (free remaining kinetic energy) U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

  47. Towards Bs** Delphi Conf 2005-011 Conf 731 • Bs¤¤! B§ K¨ observed by: • DELPHI (inclusive) • D0 (exclusive) • OPAL (inclusive) Z. Phys. C66 (1995) 19 • Rare signal dominated by large background • ! deploy sophisticated neural networks • B§! J/ K§, B§! D § • Bs¤¤ resonant signal vs. combinatorial background • ) expect CDF result this summer D0Note 5027-Conf U.Kerzel, University of Karlsruhe ---- Workshop on Heavy Quarkonia

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