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

Dive into the latest findings from Tevatron on top quark production, decay, and physics program for Run II, including cross-section measurements and mass determinations. Explore the upgrades of CDF and D0 detectors, as well as the significant role of top quarks in fundamental questions in physics. Uncover the complexities of top quark production and decay modes, along with insights on top mass, width, spin, and rare decay processes. Stay informed about top physics prospects and experimental signatures in top quark physics at Tevatron.

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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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