1 / 36

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

HERA-B Results on Heavy Flavor Production in 920 GeV Proton-Nucleus Interactions. Hermann Kolanoski Humboldt Universität zu Berlin a nd DESY Zeuthen for the HERA-B Collaboration. Charmonium production: J/ , ’,  c Open charm production: D 0 , D ± , D *

jmedeiros
Download Presentation

HERA-B Results on Heavy Flavor Production 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. HERA-B Results on Heavy Flavor Production in 920 GeV Proton-Nucleus Interactions Hermann Kolanoski Humboldt Universität zu Berlin and DESY Zeuthen for the HERA-B Collaboration • Charmonium production: J/, ’, c • Open charm production: D0, D±, D* • Hidden and open beauty production: (bb), (ns) • If time allows: pentaquark search Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  2. The HERA-B Experiment 920 GeV protons p + A  X @ s = 41.6 GeV Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  3. The HERA-B Detector Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  4. 5 MHz Pretriggers: ECAL cluster or hit coincidence in muon detector as trigger seed (custom hardware) 3 MHz First Level Trigger (FLT): Track trigger in hardware using tracking detectors behind magnet, seeding by pretriggers 20 kHz Second Level Trigger (SLT): FLT tracking confirmed, extrapolation to vertex detector, vertex fit (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 - SQM2004

  5. Data samples Data taking is finished in 2003; analysis is in progress • 150 M di-lepton trigger events (300 000 J/ψ) • 210 M minimum bias events • 35 M hard photon trigger events • 60 M “glueball” trigger events Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  6. 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  ) J/ e+ e- + - (2s) c bb (1-3s) Most results are preliminary Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  7. Study of Charmonium Suppression J/ e+ p e- scc =s0•Na a ≠ 1  “suppression” Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  8. 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) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  9. J/y from Minimum Bias data Important for cross section normalisation of di-lepton triggered data Result from both decay channels: HERA-B ~2X higherthan E771 / 789 measurements in this energy region (!?) Effects cross sections from di-lepton triggered data α = 0.955 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  10. 15% of e+e- sample J/y production: pT distribution Carbon Tungsten Preliminary results for ‹pT> (GeV/c) (n=6 fixed): Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  11. Energy dependence of <pT> Phenomenological fit <pT> = A + B √s A=0.813 ± 0.014 GeV/c B=0.0105 ± 0.0004 c-1 <pT> (GeV/c) J/→ e+e- J/→  <pT> (GeV/c) A dependence: W wider than C √s (GeV) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  12. 15% of e+e- sample J/y xF distribution J/→  Standard parametrisation: Carbon Tungsten Does this describe the data? J/→ e+e- HERA-B range -0.35 < xF < 0.15 NegativexF : nuclear medium sees fully formed charmonium states test suppression models Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  13. Comparing XF distributions • C CEM, NRQCD: calculated by R.Vogt for HERA-B energy (pp) J/→  • W CEM NRQCD E789 PYTHIA Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  14. A dependence: (xF) 2-wire runs (C, W), 10% of  data: Preliminary Preliminary Sample I Sample II FNAL E866 extended to xF = –0.3 • Samples have different wire configurations •  consistency check of acceptances • Systematic studies ongoing Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  15. Preliminary Conclusion on XF distributions • Our data are not consistent with the formula • (acceptance problems for xF > 0 ?) • data for positive xF  0from other experiments • seem to follow better this formula • Our data for carbon are consistent with the • NRQCD model and Pythia, not with CEM • ( models for pp  J/ + X) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  16. y’ production: xF and pT distributions J/→  Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  17. ’/J/ ratio: xFand pT dependence ’, J/→  xF Ratios of xF and pT distributions are consistent with being flat pT Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  18. Br·σ(ψ’) (%) Preliminary results for Br·σ(J/ψ) Production ratio y’/ J/y √s A Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  19. c / J/ production ratio observed in radiative decay Background shape from event mixing Analysis of 2002/03 data: • Comb. background by event mixing • Carbon target • In ~10% of +- statistics about 1300 c • Expect N(c) ~ 15k for full sample m (GeV/c2) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  20. c production: results Published result of 2000 ( Phys. Lett. B561(2003) 61 ) 10% of 2002/03 data R(c) = 0.21±0.05 Systematic studies ongoing Electron channel gives compatible result ECMS (GeV) HERA-B point agrees with NRQCD but NRQCD underestimates R at low Ecms Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  21. Open Charm • Search for FCNC in the decay BR(D0→+-) • see: Phys Lett B 569 (2004) 173 (hep-ex/0405059) • Open charm signals in minimum bias data • Production Cross Sections for D0, D+, D*+ • Production Ratios D+/D0 and D*+/D0 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  22. D0K+ D*+ D0 + K+ + D+K+ + Events: 189 ± 20M [MeV/c2]: 1863 ± 3  [MeV/c2]: 25 ± 3 Events: 98 ±12M [MeV/c2]: 1866 ± 2  [MeV/c2]: 15 ± 2 Events: 43 ± 8M [MeV/c2]: 145.9 ± 0.2  [MeV/c2]: 0.89 ± 0.15 Open charm signals in minimum bias data • Production Cross Sections for D0, D+, D*+ • Production Ratios D+/D0 and D*+/D0 Assuming Aα dependence with α = 1 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  23. Open Charm Production Preliminary Preliminary PYTHIA underestimates D+/D0 ratio Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  24. Lorenco and Woehri Lorenco and Woehri Open charm production: models D0 D Pythia requires K-factors ~1.5 and ~ 4.5 to describe D0 and D+ data if mc=1.5 GeV Smaller mc require smaller K factors but predict smaller increase of  at higher E Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  25. Beauty Production Detached vertex analysis RD: =5314 m pA bb + X J/ + X’ e+ e- , +- Cross sections normalised to prompt J/ HERA-B used E771/E789 data: (pN  J/ X) = (357  8  27) nb/nucleon (with  = 0.955  0.005 and energy rescaling) pA  Y(ns) + X e+ e- , +- Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  26. Open beauty production Analysis of 2002/03 data: • Full e+e- and +- statistics • Carbon + Tungsten targets • J/ acceptance: -0.35 < xF < 0.15 (90% of bb cross section) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  27. here still with 35% of data Open beauty production Relative to prompt J/ to minimize uncertainties from efficiencies, luminosity … Preliminary results with full statistics bb/J/ = 0.027  0.004  0.005 Syst. error mainly from B(bJ/) Normalizing to J/from E771 and E789 (pN  J/ X) = (357  8  27) nb/N bb= 9.8  1.4  2.0 nb/N (preliminary, normalized to FNAL data) 2000 data: Eur. Phys.J. C26(2003) 345: Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  28. Hidden beauty production Drell-Yan Drell-Yan Comb. BG Comb. BG M(e+e-) (GeV/c2) M(+-) (GeV/c2) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  29. Hidden beauty production Normalized to FNAL prompt J/ • All C and W data used (150 M evts) • Modified Craigie applied to allow for nuclear suppression: =0.990.05 Not used in fit √s (GeV) Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  30. Pentaquark Search:Experimental situation • According to a recent count*: • 12 reports of a narrow resonance (NR) • in nK+ or pK0s near 1530MeV/c2(+). • 8 reports this year of negative results on searches for +. • H1 reports a NR decaying into D*p (0c) • but Zeus reports non-observation. • NA49 reports a NR decaying into -- (--). The existence of pentaquarks is not established. If they exist, the production mechanism is unclear. *J. Pochodzalla, hep-ex/0406077 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  31. HERA-B Searched for: See hep-ex/0408048 for more details • +(1540)  p K0s  p +- • --(1862)  - -  0 - -  p - - - • At mid-rapidity in pA collisions at 920 GeV, using a large, clean (pileup  10%) minimum bias sample: 200 million interactions(A = C, Ti, W) - (1520) • Well reconstructed • cascade and reference states: • Good particle ID • Good vertex resolution Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  32. pK0s mass, Upper Limit pK0s mass (GeV/c2) for -0.3< rapidity < 0.3 event mixing mass=3.9 MeV/c2 @+ UL(95%): Carbon sensitivity 1.4 1.475 1.55 1.625 1.7 All data (with N  A0.7): Bd/dy|y=0 < 3.7 b/N (95% c.l.)@ 1530GeV/c2 < 24 b/N (95% c.l.)@ 1540GeV/c2 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  33. + mass? Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  34. Counts / 3 MeV/c2 1.4 1.6 1.8 2 2.2 Mass GeV/c2  Mass Distribution HERA-B (p + C) NA49 -- 20 10 -+ Counts / 7.5 MeV/c2 +- 10 6 ++ 1.4 1.8 2.2 2.6 Mass GeV/c2 C. Alt et al. PRL 92, 042003 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  35. NA49  Combined Plot, UL(95%) HERA-B Counts / 3 MeV/c2 Rapidity: -0.7 < y < 0.7 mass = 6.6 GeV/c2@ 1862 MeV/c2 -- B d/dy b/C Assuming N  A0.7, (95% c.l.): Bd/dy|y=0 < 2.5 b/N for m(--) =1862 GeV/c2 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

  36. Summary HERA-B collected 300k J/ and 200M min.bias events on different nuclei Preliminary results (based typically on 10-30% of statistics) are presented on: J/  cross section, 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/ D0, D+ and D*+ cross sections and relative yields Open and hidden beauty cross sections HERA-B does not observe the pentaquark states +(1540) and --(1862) Final results on these and other topics are expected in 2005 Hermann Kolanoski HU Berlin - HERA-B Results - SQM2004

More Related