1 / 47

Heavy Flavor Production at HERA-B in 920 GeV Proton-Nucleus Interactions

Charmonium production: J/ , ’,  c J/  production cross section Differential distributions, polarisation Nuclear dependence Production ratios ’/ J/ ,  c / J/  Hidden and open beauty production: ( ), (ns) production cross section  production cross section.

dillian
Download Presentation

Heavy Flavor Production at HERA-B in 920 GeV Proton-Nucleus Interactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Charmonium production: J/, ’, c • J/ production cross section • Differential distributions, polarisation • Nuclear dependence • Production ratios ’/ J/, c/ J/ • Hidden and open beauty production: ( ), (ns) • production cross section •  production cross section Heavy Flavor Production at HERA-B in 920 GeV Proton-Nucleus Interactions Hermann Kolanoski Humboldt Universität zu Berlin and DESY Zeuthen for the HERA-B Collaboration Brookhaven, 4.April 2006 Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  2. The HERA-B Experiment 920 GeV protons p + A  X @ spN = 41.6 GeV Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  3. Models of Heavy Flavour Production in Hadronic Interactions Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  4. Factorisation PDF • hadronization • Long distance (~1/(mcv)) process • non-perturbative calculations + input from experiments qq formation short distance (~1/mc) / high momentum process  perturbative calculations Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  5. Perturbative Generation:Color Singlet or Octet? JPC 0-+ 0++ 2++ JPC 1-- 1-- 1++ • Color Singlet Model (CSM): pair is produced as a color singlet with quantum numbers of the final charmonium state.  absolute predictions, but: not supported by experiment • Color Evaporation Model (CEM): pair production is the same for all charmonium states; quantum numbers arranged by “evaporation” of soft gluons.  predicts the same production dynamics of all states; cross section differences only from phase space and wave functions. • Non-Relativistic QCD Model (NRQCD): more rigorous (?) QCD treatment (singlet + octet + non-perturbative ME)  free parameters adjusted to data, predictions tested in different models, energies, final states, … Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  6. J/ e+ p e- Study of Charmonium Suppression • State formation effects: • nuclear absorption • comover absorption • multiple scattering + energy loss • Initial state effects: • shadowing (nuclear PDFs) • parton energy loss • intrinsic charm Measurement of a for 2 wire materials: a ≠ 1 “suppression” Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  7. J/ e+ formation time and length:  (xF) =   c  p e-  = (xF)boost of J/ w.r.t. nucleus xF-Dependence of Nuclear Suppression Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  8. The HERA-B Detector, Trigger and Data Samples Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  9. 184W p-beam 12C 48Ti z [cm] The HERA-B Detector Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  10. 5 MHz Pretriggers: ECAL cluster or muon hit coincidence as trigger seed (custom hardware) 3 MHz First Level Trigger (FLT): Track trigger in hardware using tracking detectors, seeding by pretriggers 20 kHz 100 Hz Second Level Trigger (SLT):FLT tracking confirmed, extrapolation to vertex detector, vertex fit (PC farm) Fourth Level Trigger (4LT):online reconstruction (and filtering) on PC farm 100 Hz The Dilepton Trigger HERA-B detector: data is read out and buffered for 12s(proton bunches cross every 96 ns, 0.5 interactions/BX) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  11. J/ collection Data samples Data taking has finished in 2003; analysis is close to be finalized Data samples: • 150 M di-lepton trigger events (300 000 J/ψ) • 210 M minimum bias events • 35 M hard photon trigger events 10 more was planned! Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  12. J/ e+ e- + - (2s) c bb (1-3s) Topics of di-lepton trigger analysis 1) pt distribution xF distribution A-dependence polarisation 2) (2s) production ratio 3) c/J/production ratio 4) bb cross section 5)  production 6) (D0  ) Most results are final or close to final Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  13. J/ Production: di-lepton triggered J/→  ~ 177,000 σ= 44 MeV/c2 J/→ e+e- ~ 108,000 J/ σ= 64 MeV/c2 J/ ~ 3000 (2S) /  (2S) ~ 1600 (2S) • absolute cross sections from di-lepton triggered data need reference cross section Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  14. Interlude:J/cross sectionfrom Minimum Bias data Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  15. J/cross sectionfrom Minimum Bias data Important for cross section normalisationof di-lepton triggered data +- e+e- • low statistics • but: efficiency and luminosity well understood •  systematic uncertainties small (usually dominant) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  16. C Ti Results: W J/y (MinB): A-Dependence and Results α = 0.96  0.01 (fixed to E866) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  17. J/y (MinB): Comparison with other Results Result from both decay channels: HERA-B ~2X higherthan E771/789 in this energy region (!?) Mesurements are in general not very consistent with each other How to get a reference cross section ??? Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  18. NRQCD Based Evaluation of J/y and y’ Cross Sections • Towards a ‚reference cross section‘: • include all measurements (J/y, y’,c) • combine by ‚QCD-inspired‘ fit F. Maltoni et al. (= HERA-B Collaborators), ‚Analysis of charmonium production at fixed-target experiments in the NRQCD approach‘, hep-ph/0601203 Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  19. Fit results at HERA-B energy s = 41.6 GeV: QCD Based Evaluation of J/y and y’ Cross Sections:Fit Results F. Maltoni et al., ‚Analysis of charmonium production at fixed-target experiments in the NRQCD approach‘, hep-ph/0601203 Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  20. … back to two-lepton triggered data:Charmonium Production Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  21. J/ differential cross sections(preliminary) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  22. (×10-4) E789 (Au) (×10-3) (×10-2) (×10-1) HERA-B (W) W Au Be C Si Ti [GeV-2] <pT>[GeV/c] (×10) E771 (Si) HERA-B (Ti) HERA-B (C) E672/E706 (Be) A pT[GeV] J/ pT distributions (nucl.dep.) standard fit: preliminary data (di-electron only), compared with p-A results at similar energy (√s = 38.8 GeV) <pT> grows logarithmically with A: Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  23. J/ pT distributions (nucl.dep.) Cronin effect <pT> grows with s: <pT>  0.8 + 0.01·s Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  24. J/y xF distribution Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  25. J/ψ: A-dependence (xF) First measurement at xF < -0.1: constant small suppression preliminary result: R.Vogt, [Nucl.Phys.A700(2002)539.]  = 0.969 ± 0.003stat± 0.021sys Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  26. J/ Polarisation usually only  is given; polarisation depends on reference system (polarisation axis in rest frame of J/) : E771, E672/E706 (Gottfried-Jackson) E866 (Collins-Soper) hadron CM (target system) CDF + (hadron CM) tan  = pT/MJ/  only for pT  0 are the systems different Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  27. ± ± ± ± ± ± HCM GJ CS ± ± ± Preliminary Polarisation Results HCM GJ CS large polarisation at pT=0  max. in CS frame  „natural“ system ? Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  28. y’/J/ production ratio Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  29. y’ production: xF distributions Tungsten Carbon J/→ J/→ , ee A-dependence:(xF) =‘-  CEM for color-1 nuclear absorption NRQCD for color-1 & -8 nuclear absorption fit with const: (E866)=-0.026±0.005 All consistent with no xF dependence. We use average of E866 and NA50: (E866, NA50)=-0.030±0.004 Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  30. y’ production: xF distributions all targets included, corrected for nuclear effects with (E866, NA50) NRQCD CEM Data are consistent with both models (and with no xF dependence) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  31. y’ production: pT distributions Carbon Tungsten J/→ J/→ • tendency for a wider pT distribution of ′ (increasing with A?) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  32. y’ production: polarisation Result: compatible with no polarisation difference Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  33. Production ratio y’/ J/y A √s CEM NRQCD Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  34. c /J/ production ratio Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  35. preliminary 2002/2003 data (di-muon sample) background: mixed events after background subtraction entries/(10 MeV/c2) m(μ+μ-γ)-m(μ+μ-) [GeV/c2] c production selection: • measurement: • fraction of J/ψ’s from χc: • kinematical distributions from the 2000 data, with 370 ± 74 χc’s(μ+μ- + e+e-): R(c) = 0.32 ± 0.06 ± 0.04 [Phys. Lett. B 561, 61 (2003)] new data: 40bigger χcstatistics (the largest ever analyzed) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  36. preliminary (a fraction of the di-muon sample) ET(γ) > 0.4 GeV background: mixed events entries/(1 MeV/c2) c2 c1 after background subtraction m(μ+μ-γ)-m(μ+μ-) [GeV/c2] c1 - c2 separation further step (?): separate different states by varying the selection cuts measure the c2/c1production ratio interesting constraints on the QCD models Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  37. E771 (p-Si) E369/ 610/ 673 (p-Be) π-A ISR (p-p) 2000 expected final precision 2002/3 prelim. E705 (p-Li) CDF (p-p) HERA-B R(c) preliminary evaluation (2002/2003 data): (21 ± 5)% of the produced J/ψ’s come from χc decays based on 1300 χc’s reconstructed in the di-muon channel (less than 10% of the total statistics) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  38. Beauty production:open& hiddenbeauty Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  39. RD: =5314 m Open and Hidden Beauty Production Detached vertex analysis open pA bb + X J/ + X’ e+ e- , +- Cross sections normalised to prompt J/ using the ‘NRQCD supported’ evaluation: (pN  J/ X) = (502  44) nb/nucleon (with  = 0.96  0.01) hidden pA  (ns) + X e+ e- , +- Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  40. Open beauty production Analysis of 2002/03 data: • e+e- and +- triggered data • C, W, Ti targets (1 for bb) • J/ acceptance: -0.35 < xF < 0.15 (90% of bb cross section) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  41. B Flavour Confirmation t = 1.39 ± 0.19 ps Long lived candidates around J/ψ mass B lifetime compatible with expected 1.54 ps (PDG) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  42. -0.35 < xF< 0.1 0 < pT < 6 GeV Open beauty production: R Relative to prompt J/ to minimize uncertainties from efficiencies, luminosity … 2000 data Combined result of 2000 and 2002/3 data: R = 0.032  0.005stat  0.004sys (syst. error mainly from B(bJ/)) PHYSICAL REVIEW D 73, 052005 (2006) 2000 data: Eur. Phys.J. C26 (2003) 345 Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  43. Production Cross section Normalizing to J/from Maltoni et al.: (pN  J/ X) = (502  44) nb/N Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  44. Hidden beauty production(1S) + (2S) + (3S) Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  45. Hidden beauty: (1S) + (2S) + (3S) 30.8±7.4 75±14 DY DY comb comb Fit: A· ((1S) + (2S) + (3S)) + B· Drell-Yan + Combinatorial (1S) : (2S) : (3S) ratio fixed to E605 results shape from MC from like-sign pairs Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  46. Fit “modified Craigie”:  NLO CEM data are compatible with =1 Hidden beauty production: Results Normalized to J/ Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

  47. Summary • HERA-B collected 300k J/ and 200M min.bias events on various nuclei • Results on charmonium production (partly preliminary): • J/  cross section (and QCD evaluation) • J/ : xF and pT distributions in a new negative xF range • J/ A dependence demonstrate a flat behavior in this region • Fraction of c and (2S) yields relative to J/ • Open and hidden beauty cross sections • Final results on J/ , c and (2S) in 2006 The end of HERA-B is close Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

More Related