Heavy Quarkonium Production at Hadron Colliders

1. Heavy Quarkonium Production at Hadron Colliders Matthew Jones Purdue University ISU HEP Seminar

2. Brookhaven, 1968 PDP-6 – 36 bit processor ISU HEP Seminar

3. First observation of charmonium ISU HEP Seminar

4. Second observation of charmonium SLAC Mark I BNL E-598 ISU HEP Seminar

5. Bottomonium ISU HEP Seminar

6. Quantum numbers: Cheat sheet: Charmonium Spectroscopy ISU HEP Seminar

7. Charmonium Spectroscopy Wolfgang Kühn – Beauty 2009 ISU HEP Seminar

8. Bottomonium Spectroscopy ISU HEP Seminar

9. Bottomonium Spectroscopy BB threshold PEP II/BaBar (2008) CESR/CUSB (1980’s) ISU HEP Seminar

10. Theoretical Description • Heavy quarks  Non-relativistic mechanics • Potential models: • Reasonably good empirical description of spectrum and transitions. • Small 1/mQ  Effective field theories • HQET: • NRQCD: ISU HEP Seminar

11. Lattice QCD... b-quark treated using HQET Important constraint for other applications... eg, B decay constants Theoretical Description ISU HEP Seminar

12. Baier and Rückl (1983): Hard part: Perturbative QCD Soft part: Non-relativistic bound state Proton structure functions Subsequent rigorous analysis by Bodwin, Braaten & Lepage Production FNAL CERN ISR CERN ISR ISU HEP Seminar

13. 6x6 pp bunches 3.5 μs bunch spacing EM/had calorimeter Central region, |η|<1 Tracking chamber Muon chambers Central region |η| < 0.6 Level 1 trigger: Muon stubs Level 2 trigger: Association with tracks 1988: First pp collisions 1992-1996: Tevatron Run I - √s = 1.8 TeV CDF detector: The Tevatron and CDF ISU HEP Seminar

14. Trigger: L1: Two muon stubs |η|<0.6 L2: match with track L3: oppositely charged muons Cross section: Acceptance: What fraction of J/ψ’s with |y|<0.6 have muons that could be reconstructed? 9-28% Depends on J/ψ polarization! Efficiency: Are the muons in the detector acceptance actually reconstructed? Secondary fraction: Measure fraction from BJ/ψX using lifetime information Run I J/ψ Cross Section 15 pb-1 |y|<0.6 pT > 5 GeV/c Pseudo proper time (cm) ISU HEP Seminar

15. 1992 measurement: No prompt/secondary separation Evidence for significant excess Run I J/ψ Cross Section PRL 69, 3704 (1992) ISU HEP Seminar

16. 1995 measurement: No feed-down from B decays NRQCD more reliable? Still a significant excess... Run I ϒ Cross Section Direct + feed-down from decays Direct ISU HEP Seminar

17. 1997 measurement: Silicon detector allows measurement of fprompt Excess and shape not explained by Structure functions Production in B decays Feed-down from states Run I J/ψ Cross Section PRL 79, 572 (1997) ISU HEP Seminar

18. Color Octet Models • Static potential models do not describe the dynamics of gluon emission within the bound state. • NRQCD: • Both components produced at • Production of P-wave color singlet: • Production of S-wave color octet: • Octet states should be included when calculating production cross section. Color singlet Color octet ISU HEP Seminar

19. Octet Sum Singlet Color Octet Models • But NRQCD is an effective field theory... • Some operators need experimental constraints • Fit to the measured pT spectrum • Compare the shapes: Cho & Leibovich, PRD 53, 6203 (1996). “χ2/NDF ... are nice and small.”

20. Color Evaporation Models • Ignore color when forming bound states. • Colorful initial state evolves to colorless asymptotic bound state by soft gluon emission. Prediction scaled by a factor of 2.2 ISU HEP Seminar

21. Optics: E/B fields transverse to direction of propagation Helicity, No helicity 0 state. Vector mesons: Transverse: Longitudinal: Polarization ISU HEP Seminar

22. NRQCD: gluon spin conserved during fragmentation at high pT, on-shell gluons (λ=±1) produce transverseψ and ϒ polarization. α 1 kT Factorization: relation between gluon virtuality (k2) and transverse momentum: at high pT, ψ’s and ϒ’s should become longitudinally polarized. α -1 Polarization Predictions (Which axis?)

23. Tevatron Run II CDFϒ(1S) polarization DØ ϒ(1S), ϒ(2S) polarization CDFψ(2S) cross section CDF J/ψ, ψ(2S) polarization (CDF Run Iϒ(1S) polarization) Run I ISU HEP Seminar

24. The CDF II Detector Muon systems: CMP CMX CMU Hadronic EM Calorimeter TOF SVX-II COT ISU HEP Seminar

25. Low backgrounds, characterized by sidebands Requires prompt/secondary classification Divide sample into 6 pT bins Higher backgrounds with properties that evolve with Mμμ Everything is prompt Analyze ϒ(1S) polarization in 8 pT bins CDF Polarization Measurements ISU HEP Seminar

26. Positive for B decays S ~ χ2 distribution J/ψ and ψ(2S) Polarization S < 8 ISU HEP Seminar

27. Polarization Templates • S-channel helicity frame: • Include detector acceptance and event selection: μ+ θ* J/ψ μ- (lab frame) (J/ψ rest frame) ISU HEP Seminar

28. Background constrained using sidebands. Simultaneous fit to extract αfit: CDF Polarization Fit ISU HEP Seminar

29. Not much polarization... Maybe becomes slightly longitudinal at high pT. Not completely consistent with Run I result... What about the ϒ(1S)? CDF J/ψ Polarization ISU HEP Seminar

30. Greater rapidity coverage Worse mass resolution... Background rapidly changing with pT... Higher pT(μ) thresholds... But no obvious problems. DØ ϒ Polarization Measurement pT < 1 GeV/c pT > 15 GeV/c CDF Run I, |y| < 0.4 NRQCD kT |y| < 1.8 ISU HEP Seminar

31. New CDF ϒ(1S) Polarization ISU HEP Seminar

32. Same fitting procedure used in Run I and in J/ψ analysis. Significant difference between transverse and longitudinal templates in most pT bins. Generally consistent with no polarization at low pT. New CDF ϒ(1S) Polarization Transverse Longitudinal ISU HEP Seminar

33. New CDF ϒ(1S) Polarization NRQCD Braaten & Lee, PRD 63, 071501R ( 2001) ISU HEP Seminar

34. New CDF ϒ(1S) Polarization |y| < 0.4 Consistent with Run I result |y| < 0.6 ISU HEP Seminar

35. New CDF ϒ(1S) Polarization Inconsistent with DØ result |y| < 1.8 Consistent with Run I result |y| < 0.6 ISU HEP Seminar

36. NRQCD predictions for ϒ(1S) polarization need input for feed-down from . states. 3.3 and 2.3σ effects Not obviously wrong Unlikely to be called an “observation” by today’s standards. But these states dilute the longitudinal polarization predicted by NRQCD... Feed-down? CDF Run I PRL 84, 2094 (2000) ISU HEP Seminar

37. Large b cross section, even at √s = 7 TeV Shouldn’t be too hard to trigger on muons... Expect reasonable samples of J/ψ with only a few pb-1. Quarkonia at the LHC ISU HEP Seminar

38. ISU HEP Seminar

39. CMS Muon Reconstruction • Stand Alone Muons reconstructed in muon system • Global Muons combine Stand Alone Muons with tracks • 95% efficient for pT > 7 GeV, |η|<2.4 • Momentum resolution: ISU HEP Seminar

40. CMS Muon Trigger • Level 1 (hardware) • 40 MHz input – 100 kHz output • Uses muon system information only, both DT/CSC at RPC • High Level Trigger (software) • 200 Hz output rate • Level 2: improve L1 analysis • Level 3: regional tracking • Single muon with pT thresholds starting at 3 GeV/c • Unprescaled at 8x1029 cm-2s-1 • Double muon with pT > 3 GeV/c Triggers for B physics ISU HEP Seminar

41. Acceptance + trigger + reconstruction efficiency approaches 70% Dominant backgrounds from semi-leptonic B decays Estimate ~60k prompt decays in 3 pb-1 at √s = 14 TeV Fewer at 7 TeV... Compare with 900 J/ψ reconstructed in 2.6 pb-1 in Run I at 1.8 TeV Sufficient for measuring J/ψ and inclusive B cross section. CMS J/ψ Selection ISU HEP Seminar

42. Calibration Triggers • CDF used a 4 GeV single-muon trigger for efficiency measurements • rate was 1.5 times that of the 1.5 GeV di-muon trigger. • CMS trigger table for luminosity of 2e30 suggests that • Rate of L1_DoubleMu3 will be 10 Hz • Rate of L1_SingleMu7 will be 30 Hz (unprescaled) • Rate of L1_SingleMu3,5 will be prescaled by 80. • This seems reasonable. • Does fine binning in pT and η make less efficient use of statistics than event-by-event weighting? • What are estimates for muon fake rates? Needs data... ISU HEP Seminar

43. Summary • Long history of tension between phenomenology and experiment. • Several theoretical frameworks: • NRQCD • kT factorization • Color evaporation models • Consistency of experiments/models? • Rapidity dependence? • Feed-down from states? • Analysis in the Collins-Soper frame? • Associated production with or ? • Lots of data from Run II yet to be analyzed • Anticipating new results from the LHC • What can you do to help? ISU HEP Seminar

44. May 18-21, 2010 at Fermilab http://conferences.fnal.gov/QWG2010/

45. Extra stuff ISU HEP Seminar

46. J/ψAcceptance definitions • CDF definition: • Strong function of both pT and y. • Typically 10-20% for pT>5 GeV/c. • Does not include muon reconstruction or trigger efficiencies. • Requires consistency checks: • Muon momentum spectrum • Fiducial coverage • Hit usage on tracker superlayers ISU HEP Seminar

47. J/ψEfficiency • Efficiencies determined from data (almost): • Track finding efficiency obtained by embedding hits from a simulated track in events from collision data and seeing if the track is reconstructed: εtrack(pT>1.5 GeV/c) ~ 0.9961 • Other efficiencies calculated using ``tag and probe’’ method: given that a muon track is reconstructed calculate the probability that it satisfies additional criteria: • εL1(pT), εL2(pT), εL3, εmuon, εχ2 • pT independent efficiency: • pT dependent efficiencies: Note: there was no L2 muon trigger for this data taking period. ISU HEP Seminar

48. Primary focus was on a measurement of the B production cross section using inclusive BJ/ψX decays. Consistent with Run I cross section measurement. Dominant uncertainties from luminosity (6%) and reconstruction efficiencies (3%). Run II J/ψ cross section ISU HEP Seminar

49. Consistent with Run I measurement Run II ψ(2S) Cross Section CSM ISU HEP Seminar

50. Hydrogen Spectroscopy Proton Electron Quantum numbers: (principal) (orbital) (spin) (total angular momentum) ISU HEP Seminar