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Top: latest results from Tevatron – cross-section and mass

Top: latest results from Tevatron – cross-section and mass. Mircea N. Coca University of Rochester, NY- CDF For the CDF and D0 collaborations FPCP 2003, Paris, June. Outline. Tevatron Status The upgrades of the CDF and D0 detectors Top Production and Decay

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Top: latest results from Tevatron – cross-section and mass

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  1. Top: latest results from Tevatron – cross-section and mass Mircea N. Coca University of Rochester, NY- CDF For the CDF and D0 collaborations FPCP 2003, Paris, June

  2. Outline • Tevatron Status • The upgrades of the CDF and D0 detectors • Top Production and Decay • Top Physics Program for Run II • First Cross-Section Measurements at 1.96 TeV, in the Dilepton and Lepton+jets channels • Top Mass Measurements in CDF (Run II) and D0 (Run I) • Top Physics Prospects Mircea Coca, U of Rochester - CDF

  3. Tevatron Upgrades/Status Integrated Luminosity • Run II upgrades • ECM increase from 1.8 →1.96 TeV→larger cross sections • Higher luminosity • Run I peak:2.4x1031 cm-2 s-1 • Run II goal:3–4x1032cm-2 s-1 • Run II peak:4.7x1031 cm-2 s-1 • Analysis-quality data accumulated by Jan ‘03 • CDF:72.0 pb-1 ( 57.5 pb-1 with silicon) • D0:30 - 50 pb-1 • Immediate goal for accelerator: • Deliver 225 pb-1 in FY 2003 • Run IIa goal:2 fb-1 Winter ‘03 Commissioning Peak Luminosity Mircea Coca, U of Rochester - CDF

  4. CDF and D0 Detectors Upgrades • New Inner tracking • silicon tracker, fiber tracker • 2T superconducting solenoid • Upgraded  system for better  -ID D0 CDF • Tracking: • Expanded silicon coverage • New drift chamber (COT) • Extended lepton-ID:||>1.0 →2.0 • End Plug calorimeter • Expanded muon coverage Mircea Coca, U of Rochester - CDF

  5. W Decay Mode ln ln W- jj jj q b b b b b t W+ ln ln jj jj g q t b b b b b (1) (2) (3) Top Production and Decay - • In proton-antiproton collisions, at 1.96 TeV, top quarks are primarily produced in pairs • single top production: • smaller rate (s =1.5 pb) • large backgrounds • not observed yet • stt increased by 30% with the CM energy increase from 1.8 →1.96 TeV • Br(tW+b) ~100% in SM • Based on the W decay modes→3 experimental signatures: ~15% ~85 % - (1) DileptonVery small backgrounds, but very small rate (2) Lepton+JetsManageable backgrounds and good rate (3) All Jets Large QCD Background Mircea Coca, U of Rochester - CDF

  6. Top Physics in Run II W helicity Top Mass • Run I: discovery mode ( Fermilab 1995) → crude look at top’s properties • Run II: precision mode→ we hope to answer fundamental questions: • Why is the top so heavy? • Is the third generation special? • Is top involved in EWSB? • Is the top the liaison to new physics? Top Width l+ Anomalous Couplings Production cross-section Top Spin W+ CP violation Top Charge Resonance production p n t b Production kinematics _ X b _ _ p t Top Spin Polarization q Rare/non SM Decays (eg: t→Zc/gc, t→H+b) W- _ q’ Branching Ratios |Vtb| Mircea Coca, U of Rochester - CDF

  7. Nobs -Nbck A . L At NLO @ s=1.96 TeV for Mtop = 175 GeV: hep-ph/0303085 (Mangano et al) Production Cross-Sections • measurement: • benchmark measurements • test of perturbative QCD • probe for physics beyond SM • non-SM production, X  tt • non-SM decay, t  Xb • SUSY models with a tt-like signal • Higgs production (WH,ZH) is a background and the opposite • Run I: • Run IIa (2fb-1): • Theoretical cross-section: • To estimate signal contribution we use 7 pb Luminosity Acceptance dstt/stt ~26 % dstt/stt ~ 7 % Mircea Coca, U of Rochester - CDF

  8. stt p E T in the Dilepton Decay Mode Backgrounds • WW/WZ, Z/g*→ tt determined from Monte Carlo (MC) • Z/g*→ee, mm from data+MC • W+jets, QCD Heavy Flavor from data Event Selection jet jet • 2 high-ET, isolated leptons (e, ) • t to be includedfor the future • large missing energy ET • D0: Raised ET cut in Z window • CDF: Veto Z-mass window events for ee, mm • at least 2 jets with large ET • large transverse energy flow HT =(ETleptons ,ETjets) l l b b n n p p p p b b E E l l T T jet jet n n Mircea Coca, U of Rochester - CDF

  9. stt Dilepton Channel (ee, em, mm) Run II Preliminary: Mircea Coca, U of Rochester - CDF

  10. em+2 jets Top Candidate Transverse View ET(e+) = 20.3 GeV pT(-) = 58.1 GeV/c ETjet(1)= 141.0 GeV ETjet(2) = 55.2 GeV ET = 91 GeV HT (e)= 216 GeV ET m- jet Longitudinal View e+ jet Mircea Coca, U of Rochester - CDF

  11. stt Dilepton Channel Data sample luminosity: 72 pb-1 Run II Preliminary: Events DF(leptons) Missing energy ET (GeV) Missing energy ET (GeV) Mircea Coca, U of Rochester - CDF

  12. Kinematics of Dilepton Candidates Run 1 L = 109 pb-1 1.8 TeV 9 events Run 2 Preliminary L= 72 pb-1 1.96TeV 5 events • Events with very large missing ET in Run 1 Mircea Coca, U of Rochester - CDF

  13. jet b  p b jet jet jet stt p E T Lepton+Jets Event Pre-Selection • A high PT isolated, charged lepton (e, m), large missing ET ( n undetected) • Large jet multiplicity ( ≥ 3 ) • Cosmic ray, electron conversion removal, dilepton veto, Z boson veto. Further selections to reduce the background B-Jet with SECVTX • topological: • ≥ 4 jets (DØ) • b jets with Soft Lepton Tag (SLT) • ≥ 3 jets, ≥ 1 SLT tag (DØ) • b jets with displaced vertex (SECVTX) • ≥ 3 jets, ≥ 1 b tag (CDF) B-Jet with SLT Mircea Coca, U of Rochester - CDF

  14. DØ Run II Preliminary a = 0.1450.02 stt Lepton+Jets Topological Backgrounds Event Pre-Selection • Preselect a sample enriched in W events • an EM object or m with large PT and large missing energy • Veto soft m’s in sample, veto dilepton events • QCD multi-jets evaluated from data vs.Njets • e+jets: due to fake jets (poand g) • m+jets: due to heavy flavor decays • W multi-jets background in the 4 jet bin estimated using data by Berends scaling law before topological cuts Mircea Coca, U of Rochester - CDF

  15. QCD Results for Topological Analysis QCD background estimation Topological Selection • ≥ 4 jets (|h| < 2.5(m) or |h| < 2.0(e), pT >15 GeV) • Aplanarity >0.065 • HT(ETjets) >180 GeV (e) • HT(ETjets+pTW)>220GeV (m) Mircea Coca, U of Rochester - CDF

  16. stt Lepton+Jets with an SLT tag Backgrounds Event Selection • preselection as for topological stt • ≥ 3 jets • softer topological cuts: • HT(SETjets)> 110 GeV • Aplanarity > 0.04 • soft m inside a jet (b→m, b→c→m) • QCD and W+jets determined from data Lepton+jets channels (SLT + Topological) combined s Run II Preliminary: Mircea Coca, U of Rochester - CDF

  17. Secondary Vertex d0 stt +Lxy Jet axis Primary Vertex Prompt Tracks Lepton+jets with a SECVTX-tag Event Selection • preselect a sample enriched in W events as already mentioned • ≥ 3 jets with ET>15 GeV • ≥ 1 jet with secondary vertex tag (SECVTX) • A jet is tagged as b jet if it has at least 2 good tracks and the displacement Lxy satisfies Lxy/xy >3 (typical xy~150 m, while Lxy~3 mm) Probability of tagging a tt event: (event tag) = 45  1  5 % Mircea Coca, U of Rochester - CDF

  18. Backgrounds Estimation Backgrounds Jet Multiplicity for the background events and the data • Mistags: from # tagged jets with Lxy<0 in inclusive jet data • W+heavy flavor: from W+jets data, b tag rate and flavor composition • Non W: from data • WW, WZ, Z→tt, single top: from Monte Carlo simulation • 1 and 2 jet bins are used as a control sample, the top events are in >= 3 jet bins • 15 Candidates in ~ 57.5 pb-1 control signal Mircea Coca, U of Rochester - CDF

  19. stt Lepton+jets - SECVTX-tagging Data sample luminosity: 57.5 pb-1 * Run II Preliminary: Mircea Coca, U of Rochester - CDF

  20. Jet3 Jet2 Lego view Jet1 Jet4 µ A “golden” lepton+jets candidate • tt l+jet candidate: Nov 02 2002 • run: 153693 event: 799494 •  + 4 jets, with 2 SECVTX b-tags SECVTX tag Event primary vertex SECVTX tag Mircea Coca, U of Rochester - CDF

  21. D0 Preliminary Top Cross-Sections Summary D0: All channels combined Run II Preliminary: Mircea Coca, U of Rochester - CDF

  22. W+ b-jet n X t t jet W- jet b-jet Top Mass: Lepton+jets Event Selection Reconstruction Method • Select ≥4 jet events, similar to stt analysis, except no requirement for a jet to be b-tagged • Each event→up to 24 solutions consistent with a top decay: • 12 different jet-partons assignments • Every combination has two solutions for the n longitudinal momentum • Impose Mt=Mt , M(j,j)=M(l,)=MW • PDG: MW, GW, Gt • 2-C fit applied, chose the event top mass corresponding to the lowest  (iff  < 10) • Parameterized templates of top masses (150, 200) GeV and bkgd • Continuous likelihood to extract top mass and statistical uncertainty 5 vertices: 20 constraints Mircea Coca, U of Rochester - CDF

  23. Top Mass Measurement • 33 candidates after event selection • 8 events with a b tagged Systematic uncertainty summary CDF Run 1 combined: Mtop = 176.1 ± 6.5 GeV/c2 Work to improve understanding of detector Mircea Coca, U of Rochester - CDF

  24. Top Mass using b-tagging • Identifying a b-jet has a great impact: • Smaller combinatorics → improves the mass resolution by ~10 % • Reduction in background→ S/B = 3, increase by 300% • Allow to loosen the 4th jet selection cuts ( 40% more events) • In 57.5 pb -1 there are11 candidates with at least one jet tagged as a b-jet • Mtop with b-tagging is coming… Mircea Coca, U of Rochester - CDF

  25. Transfer fn: resolutions, reconstruction effects Measured to be estimated Acceptance Matrix Element PDF’s Run I Mass: lepton+4 jets events • Similar with Kondo’s method, uses full set of event observables • Define a signal event probability • Define a background probability • Build an event probability where a = (Mt,c1,c2) • Build a likelihood L(a), minimize –lnL(a) to get c1, c2 and Mt i-th event observables • LO ME used, 4 jets required exclusively, additional cut on background probability (to improve the sample purity) Mircea Coca, U of Rochester - CDF

  26. Run I: Preliminary result • D0 Run I Statistics [PRD 58(1998), 052001] • Events 91→ 71 with exactly 4 jets → 22 after probability cut -log(likelihood) vs Mt likelihood vs Mt Stat : 5.6 GeV from PRD 2001 improvement on the statistical uncertainty (~2.4 stats) Run I D0 lepton+jets: 173.3± 5.6(stat) ± 5.5 (syst) GeV/c2 Mircea Coca, U of Rochester - CDF

  27. Summary & Conclusions • Top physics is extremely rich and has a great potential • Many top analyses are in progress • we re-established the benchmark top quark measurements • we are getting close to Run I precision • Improvements are underway • Better detector understanding • Increase the tagging efficiencies of b jets • Include forward leptons • We are enthusiastic about the top physics prospects at the Tevatron until first LHC results • Expect results from larger samples soon • Many measurements will supersede those of Run I • Test the Standard Model to even greater precision Mircea Coca, U of Rochester - CDF

  28. Top Physics Prospects for 2 fb-1 Measurement Est. Uncertainty Tests Mt 2-3 GeV/c2 Indirect MHdstt 7% QCD Couplingsd[sll/sl+j] 12% Non-SM Decaysd[B(t→Wb)/B(t→WX)] 2.8% ‘’d[B(t→Wb)/B(t→Xb)] 9% ‘’ d[B(t→Wlong)] 5.5% Non-SM Coup. d[B(t→WV+A)] 2.7% W helicity d[s*B(Z’→t t)] ~90 fbExotics dstbX+btX 24% Observe single top dG(t→Wb) 26% dVtb 13% CKM Matrix Mircea Coca, U of Rochester - CDF

  29. End of talk : Backup Slides Mircea Coca, U of Rochester - CDF

  30. signal background Top Mass Templates • Reconstructed top masses from data are compared to parameterized templates of top and background Monte Carlo for masses (150, 200) GeV • Use a continuous likelihood method to extract top mass and statistical uncertainty • The bump in the background shape around 130 GeV is due to the kinematic selection of the events Mircea Coca, U of Rochester - CDF

  31. Top Dilepton Kinematics Mircea Coca, U of Rochester - CDF

  32. Constraint MHiggs with a Mtop and MW DØ / CDF Run 2a Goal Mircea Coca, U of Rochester - CDF

  33. Direct Higgs Search Mircea Coca, U of Rochester - CDF

  34. s<0.1 pb Tait ‘99 2.44 ± 0.12 pb ? Steltzer, et al. ‘98 0.88 ± 0.12 pb ? Smith/Willenbrock ‘96 Single Top Mircea Coca, U of Rochester - CDF

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