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Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

6 th International Conference on Hyperons, Charm & Beauty Hadrons Illinois Institute of Technology, Chicago, IL, June 27 - July 3, 2004. Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions. Ulrich Husemann for the HERA-B Collaboration

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Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

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  1. 6th International Conference on Hyperons, Charm & Beauty Hadrons Illinois Institute of Technology, Chicago, IL, June 27 - July 3, 2004 Open and Hidden Charm Productionin 920 GeV Proton-Nucleus Collisions Ulrich Husemann for the HERA-B Collaboration Experimentelle Teilchenphysik, Universität Siegen

  2. Outline of the Talk • HERA-B detector and trigger systems • Charmonium production • Open charm production • Summary U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  3. Detector & Trigger U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  4. Inner / Outer Tracker7 layers of GEM-MSGCs (inner) and honeycomb drift chambers (outer) Wire Target 2 stations, 4 wires each (C, Ti, W) Silicon Vertex Detector8 double-layers of double-sided Si-microstrips RICHC4F10 radiator, multianode PMT focal plane ECALW/Pb-scintillator sampling calorimeter, shashlik readout, cluster pretrigger The HERA-B Detector Muon Detector4 layers of gas pixel chambers (inner) and MWPC with cathode pad readout (outer), pad-coincidence pretrigger Top View 920 GeV/c Protons Magnet 20 m 10 m 0 m U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  5. 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 10 s(proton bunches cross every 96 ns, 0.5 interactions/BX) U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  6. Data Sample 2002/2003 • Data-taking period: October 2002–February 2003 • Dilepton trigger: require 2 electrons or muons • Trigger performance: >1,000J/ per hour • Sample for charmonium studies: • 300,000 J/ • 10,000 cc • 3,500 (2S) • Study of beauty production see talk by H. Wahlberg, B3.8 • Minimum bias trigger: minimum activity in RICH/ECAL • 200 million events recorded • Strangeness and hyperon production • Pentaquark searches  see talk by A. Sbrizzi, ST.3 • Open charm production U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  7. High-mass region: Low-mass region: J/y f Approx. 3,000 eventsMass: 3674 MeV/c2Width: 53 MeV/c2 r/w (2S/3S) Approx. 177,000 eventsMass: 3095 MeV/c2Width: 44 MeV/c2 (1S) y(2S) Dilepton Spectrum: Muon Channel U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  8. Charmonium Production U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  9. J/y Production Cross Section • J/y e+e– /m+m–signals observed in minimum bias data • Determination of J/y cross section without trigger bias(systematic effects currenty under study) J/y e+e– J/y m+m– U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  10. J/y Differential Cross Section: pT • Parametrization: BroadpT coverage, good agreement of electron and muon channel 80% of e+e– sample U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  11. J/y Differential Cross Section: xF • Large acceptance for negative xF (fractional longitudinal momentum) • Parametrization: • Work on systematics ongoing 10% of e+e– sample U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  12. I. Ratio of J/y yields: fits to invariant mass spectra II. Ratio of luminosities: intercalibration of target wires III. Ratio of efficiencies: detailed detector/trigger simulation J/yA-Dependence • Test of charmonium production models in nuclear matter (nonrelativistic QCD + initial/final state interactions in nucleus) • Parametrization: •  < 1: charmonium suppression by nuclear effects • HERA-B:extract  from runs with two target wires simultaneously (carbon: A=12, tungsten: A=184) • 3 ingredients of A-dependence measurement: U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  13. J/yA-Dependence Preliminary Preliminary Sample I Sample II • Previous result of FNAL E866 extended to xF = –0.3 • Result from 10% of full m+m– sample, statistical uncertainties only • Two different combinations of carbon and tungsten wires (different acceptances): consistent results • Work on systematics ongoing U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  14. (2S) Production • Measure (2S) cross section relative to J/ reduce systematic uncertainties • eJ/y/ey(2S)= 0.72 (MC) • Preliminary result (electrons, 30% of full statistics): • Muon channel: compatible results Preliminary Preliminary R = 0.13 ± 0.02 (stat.) U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  15. cc Production • Test of charmonium production models: fraction R(cc) of J/ from radiative decaysc J/  m+ m–  Published result of 2000 data-taking (370±74 cc): I. Abt et al.,Phys. Lett. B561 (2003) 61 R(c)=0.32±0.06(stat.)±0.04(syst.) U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  16. Subtraction of combinatorial background (event mixing) • Preliminary result (15% of +– statistics,1,300 c):  compatible with 2000 results, systematic studies ongoing R(c)=0.21±0.05(stat.) R(cc): Analysis in 2002/2003 • Signal found in mass difference M(J/ ) – M(J/) U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  17. Open Charm Production U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  18. 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 Production Open charm signals in minimum bias data (charge-conjugated channels included): U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  19. Open Charm Production Preliminary Preliminary U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  20. New Limit on BR(D0+) • Search for flavor-changing neutral current decay D0+(branching fraction enhanced in some SUSY models) • 3 events in signal region:Currently best upper limitI. Abt et al., hep-ex/0405059, to be published in Phys. Lett. B • Previous limit by CDF: BR(D0+) < 2.510-6 (90% CL)D. Acosta et al.,Phys. Rev. D68 (2003) 091101 18 events 3 evt 6 events BR(D0+) < 2.010-6(90% CL) U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

  21. Summary & Outlook • HERA-B has finished data-taking • Analysis of 2002/2003 data in progress • Charmonium production: • Production cross sections and differential distributions • A-dependence of J/y production: HERA-B covers xF<0 • Production ratios: y(2S) to J/y, fraction of J/y from cc • Open charm production: • D meson production cross sections and ratios: D0, D±, D*± • New limit for FCNC decay: D0+ • Outlook: • First results of 2002/2003 run to be published soon • Stay tuned – more interesting results to come Thanks to: HERA-B charmonium & open charm working groups U. Husemann, Univ. Siegen: Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions

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