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

2. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 2 n Outline: –Tevatron and DØ detector –ϒ(1S) Production –ϒ(1S) Polarization –Summary

3. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 3 Tevatron pp-collider - -  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 1.58·10 32 (January 2006) - April 2001 Feb 2002 first data for analyses data for physics detector commissioning Jul 2002  So far reconstructed More than 1.4 fb -1 delivered &1.2 fb -1 recorded ~1 fb-1 ~10x the total Run I data

4. Penny Kasper Fermilab 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

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

6. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 6

7. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 7

8. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 8 Upsilon production n Quarkonium production is window on boundary region between perturbative and non-perturbative QCD n Factorized QCD calculations to O(α 3 ) (currently employed by PYTHIA) n color-singlet, color-evaporation, color-octet models n Different models –Shape of p t distribution –Absolute cross section –Polarization ϒ (1S) production at the Tevatron: –50% produced promptly –50% from decay of higher mass states (e.g. χ b →ϒ(1S)  )

9. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 9 Analysis Overview n Sample selection n 160 ± 10 pb-1 taken with dimuon trigger n 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) n pt (μ) > 3 GeV and |η (μ)| < 2.2 n At least one isolated μ ~ 50k ϒ (1S) events n Analysis n (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 n Get efficiencies and uncertainties

10. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 10 Fitting the Signal Signal: 3 states ( ϒ (1S), ϒ (2S), ϒ (3S)), described by Gaussians with masses m i, widths (resolution) σ i, weights c i,(i=1,2,3) –Masses m i = m 1 +  m i1 (PDG), widths σ i = σ 1 (m i /m 1 ), for i=2,3 –free parameters in signal fit: m 1, σ 1, c 1, c 2, c 3 n Background: 3rd order polynomial All plots: 3 GeV < p t (  < 4 GeV m(  ) = 9.423 ± 0.008 GeVm(  ) = 9.415± 0.009 GeVm(  ) = 9.403 ± 0.013 GeV 0 < |y  | < 0.60.6 < |y  | < 1.21.2 < |y  | < 1.8 PDG: m(ϒ(1S)) = 9.46 GeV

11. Penny Kasper Fermilab 11 d 2 σ(  (1S)) dp t × dy N(  ) L × Δp t × Δy × ε acc × ε trig × k dimu × k trk × k qual = L luminosity k dimu local muon reconstruction y rapidity k trk tracking ε acc accept.rec.eff. k qual track quality cuts ε trig trigger 0.0 < y < 0.6 0.6 < y < 1.2 1.2 < y < 1.8 ε acc 0.15 - 0.26 0.19 – 0.28 0.20 - 0.27 ε trig 0.70 0.73 0.82 k dimu 0.85 0.88 0.95 k trk 0.99 0.99 0.95 k qual 0.85 0.85 0.93 Efficiencies, correction factors… n Cross section

12. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 12 0.0 < y ϒ < 0.6 732 ± 19 (stat) ± 73 (syst) ± 48 (lum) pb 0.6 < y ϒ < 1.2 762 ± 20 (stat) ± 76 (syst) ± 50 (lum) pb 1.2 < y ϒ < 1.8 600 ± 19 (stat) ± 56 (syst) ± 39 (lum) pb 0.0 < y ϒ < 1.8 695 ± 14 (stat) ± 68 (syst) ± 45 (lum) pb CDF Run I: 0.0 < y ϒ < 0.4 680 ± 15 (stat) ± 18 (syst) ± 26 (lum) pb Results: dσ( ϒ (1S))/dy × B( ϒ (1S) → µ + µ - ) for central y bin, expect factor  1.11 increase in cross section from 1.8 TeV to 1.96 TeV (PYTHIA)

13. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 13 Normalized Differential Cross Section shape of the p t distribution does not vary much with ϒ rapidity n Reasonable agreement with calculation of Berger, Qiu, Wang

14. Penny Kasper Fermilab 14 σ(1.2 < y ϒ < 1.8)/σ(0.0 < y ϒ < 0.6 ) PYTHIA Comparison with previous results band = uncertainties of relative normalization only statistical uncertainties shown

15. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 15 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 +  cos 2 , –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

16. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 16 Systematic shift of J/psi position is -20MeV Resolution of J/psi peak is 75MeV ~ 1 fb -1 2 muons of opposite charge, Pt > 3.5 GeV Data selection

17. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 17 Dimuon mass vs. cos(  ) Mass spectrum fitted with a sum of 4 double gaussians plus background

18. Penny Kasper Fermilab Heavy Quarkonium Workshop 21 June 2006 18 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 p t ( ϒ) –First measurement of ϒ (1S) cross section at √s = 1.96 TeV. –Cross section values and shapes of dσ/dp t show only weak dependence on rapidity. –dσ/dp t is in good agreement with published results (CDF at 1.8 TeV) –Normalized dσ/dp t in good agreement with recent QCD calculations (Berger at al.) ϒ (1S) Polarization –Lots of data, results soon