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Quarkonia production with the HERA-B experiment

Quarkonia production with the HERA-B experiment. J. Spengler, MPI Heidelberg. 184 W. p-beam. 12 C. 48 Ti. z [cm]. The Hera-B Detector. Fixed target detector at e-p ring HERA, Desy High rate forward spectrometer (< 40MHz) Wire targets (different materials) in proton halo

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Quarkonia production with the HERA-B experiment

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  1. Quarkonia production with the HERA-Bexperiment J. Spengler, MPI Heidelberg

  2. 184W p-beam 12C 48Ti z [cm] The Hera-B Detector • Fixed target detector at e-p ring HERA, Desy • High rate forward spectrometer (< 40MHz) • Wire targets (different materials) in proton halo • Proton beam at 920 GeV/c (√s = 41.6 GeV) • High resolution vertexing • Very good particle ID for (e, , , K, p) • Hardware track trigger for lepton pairs • Multiple trigger level • On-line event reconstruction

  3. The Hera-B Detector Angular coverage in bending plane: 15 - 220 mrad

  4. Data Sample Data taking: 30. Oct 2002 - 3. Mar 2003 • 150 · 106 dilepton triggered events with ~300,000 J/ achieved J/ rates: 1200 - 1400 / hour in 2000: 30 - 40 / hour • 210 · 106 minimum bias events achieved logging rates: 1000 Hz (1.7 TB/d) • 90 · 106 hard photon + Glueball trigger see posters of W. Gradl (Q21) and M. Villa (Q20) see talk of A. Gorisek; posters of T. Knöpfle (S10), C. van Eldik (S8) and T. Zivko (S9) see poster of M. Bruschi (Q22)

  5. Topics 1) pt distribution xF distribution A-dependence Decay angle distribution 2) (2s) production 3) c/J/production ratio 4) bb cross section 5)  production J/ e+ e- + - (2s) c bb (1-3s) Disclaimer: All results are preliminary

  6. J/ production; e+ e- 80% of statistics ≈101,000 J/width: 64 MeV/c2 J/ (2S)   Dilepton mass accessible from 0 - 11 GeV/c2

  7. J/ production; +- J/ Approx. 3,000 eventsMass: 3674 MeV/c2Width: 53 MeV/c2 Approx. 177,000 eventsMass: 3095 MeV/c2Width: 44 MeV/c2 (2S)

  8. pT distribution of J/ 80% of e+e- sample Parameterization: stat. only Results for <pT>:

  9. xF distribution of J/ Parameterization: 10% of e+e- sample Is it adequate to describe the exp. data ?? Negative xF range accessible for the time

  10. A-dependence of J/ Parameterization of cross section: Determine  from two different targets: • C (A=12.0) and W (A=183.8) target • 25% of full e+e- sample • Ratio of efficiencies includes full detector + trigger simulation • Ratio of luminosities under investigation  norm. to E866 result stat. errors only

  11. A-dependence of J/ NRQCD pred.: R. Vogt Nucl. Phys. A700 (2002) 539 Expected stat. error for full data sample: BCKT pred.: K.G. Boreskov, A.B. Kaidalov JETP. Lett. 77 (2003) 599 HERA-B range

  12. cos distribution of J/ Parameterization: 80% of e+e- sample J/ polarization described by parameter :  = (0,1,-1)  (no, trans., long.) polarization Expected error of  vs. pT (Muon channel): Important tests of models

  13. (2S) to J/ ratio • Measure (2S)e+e- relative to J/  to reduce systematic uncertainties • Carbon target • 30% of e+e- statistics used • nJ/ = 30k • n(2S) = 650

  14. (2S) to J/ ratio • J/ /  (2S) = 0.720.01 • Stat. errors only; • Use (J/) = 357±8±27 nb/N based on E771 and E789 results R(2S) = 0.13 ± 0.02 (2S) = 46 ± 12 nb/N Systematic studies ongoing Muon channel gives compatible result

  15. c to J/ production ratio • ECAL resolution does not allow to separate c1 and c2 states (m = 46MeV). c0 neglected due to small Br. •  ≈ 0.4 Results of 2000 (Phys.Lett. B561(2003) 61: N(c) = 37074 (both +-, e+e-) R(c) = 0.320.060.04

  16. c to J/ production ratio Analysis of 2002/03 data: • Comb. background by event mixing • Carbon target • In 15% of +- statistics we find about 1300 c • Expect N(c) ~ 15k for full sample R(c) = 0.21±0.05 Systematic studies ongoing Electron channel gives compatible result m (GeV/c2)

  17. pA bb+ X, bJ/+Y Method: Detached vertex analysis to separate B signal (decay length ~7 mm) from direct J/ Results of 2000: Eur. Phys.J. C26(2003) 345: e+e- = ; +-= †

  18. pA bb+ X, bJ/+Y Analysis of 2002/03 data: • 35% of e+e- and +- statistics • Expect NB ~ 100 for full sample • Carbon + Tungsten target • J/ acceptance: -0.35<xF<0.15 (90% of bb cross section) • Preliminary results of both channels compatible • 1.5  lower than 2000 measurement

  19. Drell-Yan Drell-Yan Comb. BG Comb. BG M(e+e-) (GeV/c2) M(+-) (GeV/c2) pN  + X, +-,e+e- Drell-Yan contribution compatible with E866

  20. Not used in fit pN  + X, +-,e+e- • All C and W data used • Relative production of (1S)/(2S)/(3S) fixed on E605 data •  shapes taken from MC • Modified Craigie applied to allow for nuclear suppression: =0.990.05 √s (GeV)

  21. Summary • HERA-B has finished data taking. • Large dilepton sample (both +-,e+e-) allows for detailed study of J/ (300k), (2S),  and bb-production • Quality of data is very good • HERA-B has large acceptance (negative xF) and good particle identification • Analysis of 2002/03 data in progress • First preliminary results presented • New collaborators welcome to contribute to analysis of this rich data sample

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