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 (2S) cross section and search for narrow resonances below the Upsilon mesons at CDF

 (2S) cross section and search for narrow resonances below the Upsilon mesons at CDF. Alberto Annovi - INFN Frascati for the CDF collaboration. International Workshop on Heavy Quarkonia 2008. Nara Women's University 2-5 December 2008. The CDF detector @ Fermilab. Muon Extension |  |<1.1.

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 (2S) cross section and search for narrow resonances below the Upsilon mesons at CDF

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  1. (2S) cross section and search for narrow resonances below the Upsilon mesons at CDF Alberto Annovi - INFN Frascati for the CDF collaboration International Workshop on Heavy Quarkonia 2008 Nara Women's University 2-5 December 2008

  2. The CDF detector @ Fermilab Muon Extension ||<1.1 Central Muon ||<0.6 Ｔｅｖａｔｒｏｎ p pbar ＠1.96ＴｅＶ Solenoid +  Calorimeter system Drift Chamber Silicon Microstrip Tracker  Alberto Annovi

  3. (2S) cross section Alberto Annovi

  4. Why (2S) cross section? • Charmonium production as test of QCD models • NRQCD can account for J/ and (2S) cross-section • NRQCD *not* able to describe polarization • (2S) is clean: small feed-down from higher charmonium states • Extend differential xsec up to 30 GeV Phys. Rev. Lett. 99, 132001 (2007) Alberto Annovi

  5. Measurement principle • Select a clean di-muon sample • Unbinned fit to separate • signal from backgrond • prompt (2S) from long lived ones • fit in pT bins • Calculate acceptance, efficiency and luminosity • Get differential cross-section: Alberto Annovi

  6. Data selection • 1.1 fb-1 from low-pT dimuon trigger • Trigger selection • 2 central muons pT > 1.5 GeV • Off-line selection • 2 central muons pT > 2 GeV • 3 r- silicon (SVX II) hits / muon • tracks, muons and vertex quality cuts • Analysis kinematical limits • 2 GeV < pT((2S)) < 30 GeV • | y((2S)) | < 0.6 Alberto Annovi

  7. Fitting the data • Unbinned maximum likelihood fit variables • reconstructed mass • reconstructed ct • Signal likelihood • mass: Gaussian + crystal ball function • ct (prompt): double Gaussian • ct (long lived): exponential conv. Gaussian • Background likelihood • mass: 1st order polynomial • ct : combination of prompt, long lived symmetric and long lived asymmetric effective ct: only ’ is reconstructed Alberto Annovi

  8. Fit projections 5.5 < pT < 6.0 GeV CDF preliminary 1.1fb-1 CDF preliminary 1.1fb-1 4213 prompt 1023 long liv. signal events 5236 (2S) signal events Alberto Annovi

  9. Acceptance and efficiency • Geometric acceptance from CDF simulation • (2S) generated uniform in , pT and y • (2S) decayed with EVTGEN • different polarization are generated • Trigger efficiency measured on data • Offline reconstruction efficiency • measured on data in combination with MC • Nominal luminosity 1.1fb-1 • effective luminosity is 0.95fb-1 • due to trigger dynamic prescale @ high luminosity Alberto Annovi

  10. Polarization • Acceptance depends upon polarization • Acceptance and its systematics are determined assuming: • prompt :  = 0.01 ± 0.13 • A=2% @ pT=3 GeV • A=20% @ pT=23 GeV • from B decays • eff = 0.35 ± 0.25 ± 0.03 • A=1.5% @ pT=3 GeV • A=19% @ pT=23 GeV • Inclusive measurement uses weighted average acceptance Phys. Rev. Lett. 99, 132001 (2007) Alberto Annovi

  11. Systematics uncertanities Alberto Annovi

  12. CDF preliminary 1.1fb-1 Differential cross-section Inclusive total cross-section: Prompt component tot. xsec: 2 < pT((2S)) > 30 GeV | y((2S)) | < 0.6 preliminary Alberto Annovi

  13. Comparison with Run I CDF preliminary 1.1fb-1 B decay points scaled down by 0.1 Run II (1.96TeV) points centered on bin <pT>. Run I (1.8TeV) points are on bin centers. Alberto Annovi

  14. Ratio of cross-sections Ratio of (2S) to J/ Ratio of ratio CDF preliminary 1.1fb-1 CDF preliminary 1.1fb-1 long lived prompt PRD to be submitted soon http://www-cdf.fnal.gov/physics/new/bottom/071018.blessed-psi2S-xsec/ Alberto Annovi

  15. Comparisons with NNLO* Yield better described at low-pT. High-pT data (>17 GeV) from this measurement not compatible with theory. Theory progress here is welcome! NNLO* CSM Theory curve courtesy of P. Artoisenet et al., according to Phys.Rev.Lett.101:152001,2008. [arXiv:0806.3282] see also proceedings for HP2008 submitted to EPJC Alberto Annovi

  16. search for narrow resonances below the Upsilon mesons Alberto Annovi

  17. Why looking for light dimuon resonances? • Low mass sbottom not completely excluded • D.G. Aschman et al., Phys.Rev.Lett.39:124 (1977) • A. M. Boyarski et al., Phys. Rev. Lett. 34, 762 (1975) • CLEO, Phys. Rev. D 63, 051101 (2001) • DELPHI, Phys. Lett. B 444, 491 (1998) • Some models include low mass sbottom • M. Carena et al., Phys.Rev.Lett.86:4463 (2001) • E. L. Berger et al., Phys.Rev.Lett.86:4231 (2001) Alberto Annovi

  18. Dimuon spectrum in Run I data 3.5 excess G. Apollinari et al. using CDF Run I data Phys.Rev.D72:092003,2005 Alberto Annovi

  19. Analysis method • Search for prompt dimuon pairs • look for resonances (epsilon) with detector resolution • Report results as • *BR relative to Y(1S) • Leptonic width of hypotetical sbottomonium • Assumptions for *BR relative to Y(1S) • Assume  to be unpolarized • Assume pT to scale with mass w.r.t. (1S) • i.e. <pT>/ <pTY(1S)> = mEpsi/ mY(1S) • Assume  to be prompt • Not produced inside a jet, i.e. isolated Alberto Annovi

  20. Data sample • 630pb-1 from dimuon trigger • June 2006 - January 2007 • Trigger selection • 1st central muon pT > 3 GeV, || < 0.6 • 2nd muon pT > 2 GeV, || < 1.1 Alberto Annovi

  21. Isolation tracks pT<4GeV  Data selection • First reconstruct all dimuon candidates • passing trigger confirmation • Data contains a large contamination of dimuons from • bbbar and ccbar • Require isolation < 4 GeV for both muons • Isolation is sum of all tracks pT in a cone around each muon • Promptness cuts on 3D vertex • Vertex probability > 0.001 • Lxy/xy < 3 (Lxy w.r.t primary vertex) Alberto Annovi

  22. Dimuon mass spectrum Alberto Annovi

  23. Upsi region fit • Fit with • Bkg: 5th degree polynomial • Sig: Double Gaussians • Fit results • 52780 ± 350 Y(1S) events • bkg of 13976 events • 9.3 < M < 9.55 GeV • MY(1S) 9459 ± 1 MeV • M 52 ± 1 MeV Alberto Annovi

  24. Resonance search 2/NDF 66/55 Probability 0.14 Background only: 5th degree polynomial fit Alberto Annovi

  25. Resonance search Add a Gaussian to the fit • We fit in the region 6 to 9.1 GeV • perform 108 fits in steps of 25MeV starting at 6.3 GeV • Peak width is fixed to expectations from simulation: 40 to 48 MeV Probe Gaussian in blue Alberto Annovi

  26. Upper limits • 90% Bayesian limits • assuming prior probability flat above zero • acceptance correction is • Arel=65.5% of Y(1S) at 6.3 GeV • Arel=97.4% of Y(1S) at 9.0 GeV Where N is number of reconstructed events Alberto Annovi

  27. Upper limits Red is expected limit. Blue is observed limit. Systematic is 6% • relative acceptance due to Y polarization • resonance line shape modeling The excess in PRD72:092003,2005 was (36±9)*10-3 at 7.2 GeV 90% CL Alberto Annovi

  28. Upper limits Sbottomonium leptonic width 90% CL 90% CL http://www-cdf.fnal.gov/physics/new/bottom/080703.blessed-Dimuon_resonance/ Alberto Annovi

  29. Conclusions • (2S) cross section in Run II • provides data up to 30 GeV for the first time • adds input for quarkonia production understanding • Search for narrow resonances below the Upsilon mesons • no evidence for new signals --> set limits • almost exclude light sbottomonium (6.3 < m < 9 GeV) • not fully excluded within (not shown) theoretical uncertainties Alberto Annovi

  30. BACKUP Alberto Annovi

  31. CDF preliminary 1.1fb-1 Comparison with Run I Run II (1.96TeV) points scaled to 1.8 GeV (-14%) centered on bin <pT>. Run I (1.8TeV) points are on bin centers. NRQCD uses a fit to Run I data described in E. Braaten et. Al., hep-ph/0008091 Phys.Rev.D63:094006,2001 Alberto Annovi

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