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Upsilon production D Ø

Upsilon production D Ø. Penny Kasper Fermilab (D Ø collaboration) 29 June 2006 Heavy Quarkonium Workshop Brookhaven, June 2006. Outline: Tevatron and D Ø detector ϒ (1S) Production ϒ (1S) Polarization Summary. -. Run I (1992 – 1995) √s = 1.8 TeV delivered ~ 260 pb -1

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Upsilon production D Ø

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  1. Upsilon production DØ Penny Kasper Fermilab (DØ collaboration) 29 June 2006 Heavy Quarkonium Workshop Brookhaven, June 2006 Heavy Quarkonium Workshop 21 June 2006

  2. Outline: • Tevatron and DØ detector • ϒ(1S) Production • ϒ(1S) Polarization • Summary Heavy Quarkonium Workshop 21 June 2006

  3. - • Run I (1992 – 1995) √s = 1.8 TeV • delivered ~ 260 pb-1 • Run II (2002 – ) √s = 1.96 TeV • collisions every 396 ns • rate to tape 50 Hz • delivers ~ 15 pb-1/week (January 2006) • max luminosity 1.58·1032 (January 2006) - Tevatron pp-collider More than 1.4 fb-1 delivered &1.2 fb-1 recorded data for physics Feb 2002 April 2001 Jul 2002 first data for analyses detector commissioning • So far reconstructed ~1 fb-1 ~10x the total Run I data Heavy Quarkonium Workshop 21 June 2006

  4. The DZero Experiment • Silicon tracker • Coverage up to |η| <2 • New Layer 0 • Fiber tracker • Coverage up to | η | <2 • 8 double layers • Solenoid (2 Tesla) • Forward + central muon system • Coverage up to | η | <2 • Three level trigger system • Outputs 50 Hz Heavy Quarkonium Workshop 21 June 2006

  5. DØ Muon Detector • 3 layers • Drift tubes and scintillation counters • One layer (A) inside of 1.8 T toroid • Good coverage: • Central |η| < 1 PDT • Forward 1 < |η| < 2 MDT • Fast and efficient trigger Heavy Quarkonium Workshop 21 June 2006

  6. Quarkonium production is window on boundary region between perturbative and non-perturbative QCD Factorized QCD calculations to O(α3) (currently employed by PYTHIA) color-singlet, color-evaporation, color-octet models Different models Shape of pt distribution Absolute cross section Polarization ϒ(1S) production at the Tevatron: 50% produced promptly 50% from decay of higher mass states (e.g. χb →ϒ(1S) ) Upsilon production Heavy Quarkonium Workshop 21 June 2006

  7. Analysis Overview • Sample selection • 160 ± 10 pb-1 taken with dimuon trigger • Opposite sign muons with hits in all three layers of the muon system, matched to a track in the central tracking system (with hit in SMT) • pt (μ) > 3 GeV and |η (μ)| < 2.2 • At least one isolated μ • ~ 50k ϒ(1S) events • Analysis • (μ+μ-) mass resolution functions obtained from J/ψ and MC studies • Fit (μ+μ-) mass spectra for different y and pt bins, assuming 3 ϒ states and background • Get efficiencies and uncertainties Heavy Quarkonium Workshop 21 June 2006

  8. Fitting the Signal • Signal: 3 states (ϒ(1S), ϒ(2S), ϒ(3S)), described by Gaussians with masses mi, widths (resolution) σi, weights ci ,(i=1,2,3) • Masses mi= m1+ m i1(PDG), widths σi= σ1• (mi/m1), for i=2,3 • free parameters in signal fit: m1, σ1, c1, c2, c3 • Background: 3rd order polynomial PDG: m(ϒ(1S)) = 9.46 GeV m(¡) = 9.423 ± 0.008 GeV m(¡) = 9.415± 0.009 GeV m(¡) = 9.403 ± 0.013 GeV 0 < |y¡ | < 0.6 0.6 < |y¡ | < 1.2 1.2 < |y¡ | < 1.8 All plots: 3 GeV < pt(¡) < 4 GeV Heavy Quarkonium Workshop 21 June 2006

  9. N(¡) d2σ(¡(1S)) = L × Δpt × Δy × εacc× εtrig× kdimu× ktrk× kqual dpt× dy Efficiencies, correction factors… • Cross section L luminosity kdimu local muon reconstruction y rapidity ktrk tracking εacc accept.•rec.eff. kqual track quality cuts εtrig trigger 0.0 < y < 0.6 0.6 < y < 1.2 1.2 < y < 1.8 εacc 0.15 - 0.26 0.19 – 0.28 0.20 - 0.27 εtrig 0.70 0.73 0.82 kdimu 0.85 0.88 0.95 ktrk 0.99 0.99 0.95 kqual 0.85 0.85 0.93

  10. Results: dσ(ϒ(1S))/dy × B(ϒ(1S) → µ+µ-) 0.0 < yϒ < 0.6 732 ± 19 (stat) ± 73 (syst)± 48 (lum) pb 0.6 < yϒ < 1.2 762 ± 20 (stat) ± 76 (syst) ± 50 (lum) pb 1.2 < yϒ < 1.8 600 ± 19 (stat) ± 56 (syst) ± 39 (lum) pb 0.0 < yϒ < 1.8 695 ± 14 (stat) ± 68 (syst) ± 45 (lum) pb CDF Run I: 0.0 < yϒ < 0.4 680 ± 15 (stat) ± 18 (syst) ± 26 (lum) pb for central y bin, expect factor  1.11 increase in cross section from 1.8 TeV to 1.96 TeV (PYTHIA) Heavy Quarkonium Workshop 21 June 2006

  11. Normalized Differential Cross Section • shape of the pt distribution does not vary much with ϒrapidity • Reasonable agreement with calculation of Berger, Qiu, Wang Heavy Quarkonium Workshop 21 June 2006

  12. Comparison with previous results only statistical uncertainties shown PYTHIA σ(1.2 < yϒ < 1.8)/σ(0.0 < yϒ < 0.6) band = uncertainties of relative normalization

  13. Polarization • NRQCD predicts that (1S) will be produced with increasing transverse polarization as pt increases. The Color Evaporation Model predicts no polarization. • Angular distribution ~ 1 +  cos2, • Where  is the angle between + in the S rest frame and the direction of the S in the lab frame •  = +1 Transverse polarization •  = -1 Longitudinal polarization Heavy Quarkonium Workshop 21 June 2006

  14. Data selection ~ 1 fb -1 2 muons of opposite charge, Pt > 3.5 GeV Systematic shift of J/psi position is -20MeV Resolution of J/psi peak is 75MeV Heavy Quarkonium Workshop 21 June 2006

  15. Dimuon mass vs. cos() Mass spectrum fitted with a sum of 4 double gaussians plus background Heavy Quarkonium Workshop 21 June 2006

  16. Summary • ϒ(1S) cross-section • Presented measurement of ϒ(1S) cross section • BR(→μμ) for 3 different rapidity bins out to y(ϒ) = 1.8, as a function of pt(ϒ) • First measurement of ϒ(1S) cross section at √s = 1.96 TeV. • Cross section values and shapes of dσ/dpt show only weak dependence on rapidity. • dσ/dpt is in good agreement with published results (CDF at 1.8 TeV) • Normalized dσ/dpt in good agreement with recent QCD calculations (Berger at al.) • ϒ(1S) Polarization • Lots of data, results soon Heavy Quarkonium Workshop 21 June 2006

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