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What a Difference the Last 2 Years Have Made!

Physics at the Tevatron. What a Difference the Last 2 Years Have Made!. From IMFP2006 → IMFP2008. Rick Field University of Florida ( for the CDF & D0 Collaborations ). Jet Physics, Heavy Quarks (b, t) Vector Bosons ( g , W, Z). Palacio de Jabalquinto, Baeza, Spain. Happy Leap Year Day!.

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What a Difference the Last 2 Years Have Made!

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  1. Physics at the Tevatron What a Difference the Last 2 YearsHave Made! From IMFP2006 → IMFP2008 Rick Field University of Florida (for the CDF & D0 Collaborations) Jet Physics, Heavy Quarks (b, t) Vector Bosons (g, W, Z) Palacio de Jabalquinto, Baeza, Spain Happy Leap Year Day! CDF Run 2 Rick Field – Florida/CDF/CMS

  2. 23 tt-pairs/month! Tevatron Performance The data collected since IMFP 2006 more than doubled the total data collected in Run 2! IMFP 2008 ~3.3 fb-1 delivered ~2.8 fb-1 recorded ~1.6 fb-1 IMFP 2006 ~1.5 fb-1 delivered ~1.2 fb-1 recorded Integrated Luminosity per Year • Luminosity records (IMFP 2008): • Highest Initial Inst. Lum: ~2.92×1032 cm-2s-1 • Integrated luminosity/week: 45 pb-1 • Integrated luminosity/month: 165 pb-1 • Luminosity Records (IMFP 2006): • Highest Initial Inst. Lum: ~1.8×1032 cm-2s-1 • Integrated luminosity/week: 25 pb-1 • Integrated luminosity/month: 92 pb-1 Rick Field – Florida/CDF/CMS

  3. Many New Tevatron Results! Some of the CDF Results since IMFP2006 • Observation of Bs-mixing: Δms = 17.77 ± 0.10 (stat) ± 0.07(sys). • Observation of new baryon states: Sb and Xb. • Observation of new charmless: B→hh states. • Evidence for Do-Dobar mixing . • Precision W mass measurement: Mw = 80.413 GeV (±48 MeV). • Precision Top mass measurement: Mtop = 170.5 (±2.2) GeV. • W-width measurement: 2.032 (±0.071) GeV. • WZ discovery (6-sigma): s = 5.0 (±1.7) pb. • ZZ evidence (3-sigma). • Single Top evidence (3-sigma) with 1.5 fb-1: s = 3.0 (±1.2) pb. • |Vtb|= 1.02 ± 0.18 (exp) ± 0.07 (th). • Significant exclusions/reach on many BSM models. • Constant improvement in Higgs Sensitivity. I cannot possibility cover all the great physics results from the Tevatron since IMFP 2006! I will show a few of the results! Rick Field – Florida/CDF/CMS

  4. ~9 orders of magnitude Higgs ED In Search of Rare Processes We might get lucky! We are beginning to measure cross-sections ≤ 1 pb! s(pT(jet) > 525 GeV) ≈ 15 fb! PRODUCTION CROSS SECTION (fb) 1 pb W’, Z’, T’ 15 fb Rick Field – Florida/CDF/CMS

  5. “Theory Jets” “Tevatron Jets” Jets at Tevatron • Experimental Jets: The study of “real” jets requires a “jet algorithm” and the different algorithms correspond to different observables and give different results! Next-to-leading order parton level calculation 0, 1, 2, or 3 partons! • Experimental Jets: The study of “real” jets requires a good understanding of the calorimeter response! • Experimental Jets: To compare with NLO parton level (and measure structure functions) requires a good understanding of the “underlying event”! Rick Field – Florida/CDF/CMS

  6. Jet Corrections • Calorimeter Jets: • We measure “jets” at the “hadron level” in the calorimeter. • We certainly want to correct the “jets” for the detector resolution and effieciency. • Also, we must correct the “jets” for “pile-up”. • Must correct what we measure back to the true “particle level” jets! • Particle Level Jets: • Do we want to make further model dependent corrections? • Do we want to try and subtract the “underlying event” from the “particle level” jets. • This cannot really be done, but if you trust the Monte-Carlo models modeling of the “underlying event” you can try and do it by using the Monte-Carlo models (use PYTHIA Tune A). • Parton Level Jets: • Do we want to use our data to try and extrapolate back to the parton level? • This also cannot really be done, but again if you trust the Monte-Carlo models you can try and do it by using the Monte-Carlo models. The “underlying event” consists of hard initial & final-state radiation plus the “beam-beam remnants” and possible multiple parton interactions. Rick Field – Florida/CDF/CMS

  7. CTEQ4M PDFsCTEQ4HJ PDFs Run I CDF Inclusive Jet Data(Statistical Errors Only)JetClu RCONE=0.7 0.1<||<0.7R=F=ET /2 RSEP=1.3 CTEQ4HJ CTEQ4M Inclusive Jet Cross Section (CDF) • Run 1 showed a possible excess at large jet ET (see below). • This resulted in new PDF’s with more gluons at large x. • The Run 2 data are consistent with the new structure functions (CTEQ6.1M). IMFP2006 Rick Field – Florida/CDF/CMS

  8. Inclusive Jet Cross Section (CDF) • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • Data corrected to the hadron level • L= 1.04 fb-1 • 0.1 < |yjet| < 0.7 • Compared with NLO QCD IMFP2006 today 1.13 fb-1 s(pT > 525 GeV) ≈ 15 fb! Sensitive to UE + hadronization effects for PT < 200 GeV/c! Rick Field – Florida/CDF/CMS

  9. KT Algorithm • kT Algorithm: • Cluster together calorimeter towers by their kT proximity. • Infrared and collinear safe at all orders of pQCD. • No splitting and merging. • No ad hoc Rsep parameter necessary to compare with parton level. • Every parton, particle, or tower is assigned to a “jet”. • No biases from seed towers. • Favored algorithm in e+e- annihilations! KT Algorithm Will the KT algorithm be effective in the collider environment where there is an “underlying event”? Raw Jet ET = 533 GeV Raw Jet ET = 618 GeV CDF Run 2 Only towers with ET > 0.5 GeV are shown Rick Field – Florida/CDF/CMS

  10. KT Inclusive Jet Cross Section (CDF) • KT Algorithm (D = 0.7) • Data corrected to the hadron level • L= 385 pb-1 • 0.1 < |yjet| < 0.7 • Compared with NLO QCD. IMFP2006 today 1.0 fb-1 Sensitive to UE + hadronization effects for PT < 200 GeV/c! Rick Field – Florida/CDF/CMS

  11. from Run I High x Gluon PDF • Forward jets measurements put constraints on the high x gluon distribution! Big uncertainty for high-x gluon PDF! Uncertainty on gluon PDF (from CTEQ6) x Forward Jets high x low x Rick Field – Florida/CDF/CMS

  12. KT Forward Jet Cross Section (CDF) • KT Algorithm (D = 0.7). • Data corrected to the hadron level. • L = 385 pb-1. • Five rapidity regions: • |yjet| < 0.1 • 0.1 < |yjet| < 0.7 • 0.7 < |yjet| < 1.1 • 1.1 < |yjet| < 1.6 • 1.6 < |yjet| < 2.1 • Compared with NLO QCD today 1.0 fb-1 IMFP2006 Rick Field – Florida/CDF/CMS

  13. New since IMFP2006 Forward Jet Cross Section (CDF) • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • Data corrected to the hadron level • L = 1.13 pb-1. • Five rapidity regions: • |yjet| < 0.1 • 0.1 < |yjet| < 0.7 • 0.7 < |yjet| < 1.1 • 1.1 < |yjet| < 1.6 • 1.6 < |yjet| < 2.1 • Compared with NLO QCD 1.0 fb-1 Rick Field – Florida/CDF/CMS

  14. New since IMFP2006 DiJet Cross Section (CDF) CDF Run II Preliminary • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • Data corrected to the hadron level • L= 1.13 fb-1 • |yjet1,2| < 1.0 • Compared with NLO QCD Sensitive to UE + hadronization effects! Rick Field – Florida/CDF/CMS

  15. Inclusive Jet versus DiJet (CDF) Inclusive Jet (CDF) DiJet (CDF) • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • CTEQ6.1M m = PT/2 • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • CTEQ6.1M m = mean(PT1,PT2) Rick Field – Florida/CDF/CMS

  16. New since IMFP2006 CDF DiJet Event: M(jj) ≈ 1.4 TeV ETjet1 = 666 GeV ETjet2 = 633 GeV Esum = 1,299 GeV M(jj) = 1,364 GeV Exclusive p+p → p+p+e++e- (16 events) s = 1.6 ± 0.3 pb M(jj)/Ecm≈ 70%!! CDF Run II Rick Field – Florida/CDF/CMS

  17. “Towards”, “Away”, “Transverse” Look at the charged particle density, the charged PTsum density and the ETsum density in all 3 regions! Df Correlations relative to the leading jet Charged particles pT > 0.5 GeV/c |h| < 1 Calorimeter towers ET > 0.1 GeV |h| < 1 • Look at correlations in the azimuthal angle Df relative to the leading charged particle jet (|h| < 1) or the leading calorimeter jet (|h| < 2). • Define |Df| < 60o as “Toward”, 60o < |Df| < 120o as “Transverse ”, and |Df| > 120o as “Away”. Each of the three regions have area DhDf = 2×120o = 4p/3. “Transverse” region is very sensitive to the “underlying event”! Rick Field – Florida/CDF/CMS

  18. Overall Totals (|h| < 1) ETsum = 775 GeV! • Data at 1.96 TeV on the overall number of charged particles (pT > 0.5 GeV/c, |h| < 1) and the overall scalar pT sum of charged particles (pT > 0.5 GeV/c, |h| < 1) and the overall scalar ET sum of all particles (|h| < 1) for “leading jet” events as a function of the leading jet pT. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level).. “Leading Jet” ETsum = 330 GeV PTsum = 190 GeV/c Nchg = 30 Rick Field – Florida/CDF/CMS

  19. “Towards”, “Away”, “Transverse” • Data at 1.96 TeV on the density of charged particles, dN/dhdf, with pT > 0.5 GeV/c and |h| < 1 for “leading jet” events as a function of the leading jet pT for the “toward”, “away”, and “transverse” regions. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level). “Leading Jet” Factor of ~13 Factor of ~16 Factor of ~4.5 • Data at 1.96 TeV on the charged particle scalar pT sum density, dPT/dhdf, with pT > 0.5 GeV/c and |h| < 1 for “leading jet” events as a function of the leading jet pT for the “toward”, “away”, and “transverse” regions. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level). • Data at 1.96 TeV on the particle scalar ET sum density, dET/dhdf, for |h| < 1 for “leading jet” events as a function of the leading jet pT for the “toward”, “away”, and “transverse” regions. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A at the particle level (i.e. generator level). Rick Field – Florida/CDF/CMS

  20. The Leading Jet Mass • Data at 1.96 TeV on the leading jet invariant mass for “leading jet” events as a function of the leading jet pT. The data are corrected to the particle level (with errors that include both the statistical error and the systematic uncertainty) and are compared with PYTHIA Tune A and HERWIG (without MPI) at the particle level (i.e. generator level). “Leading Jet” Off by ~2 GeV • Shows the Data - Theory for the leading jet invariant mass for “leading jet” events as a function of the leading jet pT for PYTHIA Tune A and HERWIG (without MPI). Rick Field – Florida/CDF/CMS

  21. bb DiJet Cross Section (CDF) ≈ 85% purity! Collision point • b-quark tag based on displaced vertices. Secondary vertex mass discriminates flavor. • Require two secondary vertex tagged b-jets within |y|< 1.2 and study the two b-jets (Mjj, Dfjj, etc.). Rick Field – Florida/CDF/CMS

  22. The Sources of Heavy Quarks Leading-Log Order QCD Monte-Carlo Model (LLMC) Leading Order Matrix Elements • We do not observe c or b quarks directly. We measure D-mesons (which contain a c-quark) or we measure B-mesons (which contain a b-quark) or we measure c-jets (jets containing a D-meson) or we measure b-jets (jets containing a B-meson). (structure functions) × (matrix elements) × (Fragmentation) + (initial and final-state radiation: LLA) Rick Field – Florida/CDF/CMS

  23. Amp(gg→QQg) = s(gg→QQg) = Other Sources of Heavy Quarks • In the leading-log order Monte-Carlo models (LLMC) the separation into “flavor creation”, “flavor excitation”, and “gluon splitting” is unambiguous, however at next to leading order the same amplitudes contribute to all three processes! “Flavor Excitation” (LLMC) corresponds to the scattering of a b-quark (or bbar-quark) out of the initial-state into the final-state by a gluon or by a light quark or antiquark. “Gluon-Splitting” (LLMC) is where a b-bbar pair is created within a parton shower or during the the fragmentation process of a gluon or a light quark or antiquark. Here the QCD hard 2-to-2 subprocess involves only gluons and light quarks and antiquarks. and there are interference terms! Next to Leading Order Matrix Elements 2 + + Rick Field – Florida/CDF/CMS

  24. “Flavor Creation” b-quark Initial - State Radiation Proton AntiProton Underlying Event Underlying Event Final - State b-quark Radiation bb DiJet Cross Section (CDF) IMFP2006 • ET(b-jet#1) > 35 GeV, ET(b-jet#2) > 32 GeV, |h(b-jets)| < 1.2. Preliminary CDF Results: sbb = 34.5  1.8 10.5 nb QCD Monte-Carlo Predictions: Differential Cross Section as a function of the b-bbar DiJet invariant mass! JIMMY Runs with HERWIG and adds multiple parton interactions! JIMMY: MPI J. M. Butterworth J. R. Forshaw M. H. Seymour Adding multiple parton interactions (i.e. JIMMY) to enhance the “underlying event” increases the b-bbar jet cross section! Rick Field – Florida/CDF/CMS

  25. New since IMFP2006 bb DiJet Cross Section (CDF) • ET(b-jet#1) > 35 GeV, ET(b-jet#2) > 32 GeV, |h(b-jets)| < 1.2. Systematic Uncertainty Preliminary CDF Results: sbb = 5664  168  1270pb QCD Monte-Carlo Predictions: Predominately Flavor creation! Sensitive to the “underlying event”! Rick Field – Florida/CDF/CMS

  26. New since IMFP2006 bb DiJet Df Distribution (CDF) • Large Df (i.e. b-jets are “back-to-back”) is predominately “flavor creation”. • Small Df (i.e. b-jets are near each other) is predominately “flavor excitation” and “gluon splitting”. • It takes NLO + “underlying event” to get it right! Rick Field – Florida/CDF/CMS

  27. New since IMFP2006 Z + b-Jet Production (CDF) IMFP2006 • Important background for new physics! • Leptonic decays for the Z. • Z associated with jets. • CDF: JETCLU, D0: • R = 0.7, |hjet| < 1.5, ET >20 GeV • Look for tagged jets in Z events. 1.5 fb-1 L = 335 pb-1 today Extract fraction of b-tagged jets from secondary vertex mass distribution: NO assumption on the charm content. Sensitive to the “underlying event”! Rick Field – Florida/CDF/CMS

  28. Z-boson Cross Section (CDF) L = 72 pb-1 IMFP2006 QCDDrell-Yan • Impressive agreement between experiment and NNLO theory (Stirling, van Neerven)! Rick Field – Florida/CDF/CMS

  29. Z-boson Cross Section (CDF) IMFP2006 L = 337 pb-1 • Impressive agreement between experiment and NNLO theory (Stirling, van Neerven)! Rick Field – Florida/CDF/CMS

  30. New since IMFP2006 Zcc Zcp Zpp Z-Boson Rapidity Distribution • Measure ds/dy for Z→e+e-. Use electrons in the central (C) and plug (P) calorimeter. • Parton momentum fractions x1 and x2 determine the Z boson rapidity, yZ. • Production measurement in high yZ region probes high x region of PDF’s. • Plug-plug electrons, ZPP, are used to probe the high x region! Plug-Plug electrons! 1.1fb-1 91,362 events 66 < MZ < 116 GeV Rick Field – Florida/CDF/CMS

  31. New since IMFP2006 Z-Boson Rapidity Distribution • CDF measured ds/dy for Z/g* compared with an NL0 calculation using CTEQ6.1M PDF. • The NLO theory is scaled to the measured s(Z)! • No PDF or luminosity uncertainties included. NLO + CTEQ6.1 PDF NLO + MRST PDF NLL0 + NNL0 MRST PDF Rick Field – Florida/CDF/CMS

  32. Channel for Z→ττ: electron + isolated track One t decays to an electron: τ→e+X (ET(e)> 10 GeV) . One t decays to hadrons: τ → h+X (pT > 15GeV/c). Remove Drell-Yan e+e- and apply event topology cuts for non-Z background. Signal cone Isolation cone The Z→tt Cross Section (CDF) • Taus are difficult to reconstruct at hadron colliders • Exploit event topology to suppress backgrounds (QCD & W+jet). • Measurement of cross section important for Higgs and SUSY analyses. • CDF strategy of hadronic τ reconstruction: • Study charged tracks define signal and isolation cone (isolation = require no tracks in isolation cone). • Use hadronic calorimeter clusters (to suppress electron background). • π0 detected by the CES detector and required to be in the signal cone. • CES: resolution 2-3mm, proportional strip/wire drift chamber at 6X0 of EM calorimeter. Rick Field – Florida/CDF/CMS

  33. 1 and 3 tracks, opposite sign same sign, opposite sign The Z→tt Cross Section (CDF) • CDF Z→ττ (350 pb-1): 316 Z→ττ candidates. • Novel method for background estimation: main contribution QCD. • τ identification efficiency ~60% with uncertainty about 3%! IMFP2006 264 ± 23 (stat) ± 14 (sys) ± 15 (lum) Rick Field – Florida/CDF/CMS

  34. Higgs → tt Search (CDF) events IMFP2006 140 GeV Higgs Signal! 1 event • Data mass distribution agrees with SM expectation: • MH > 120 GeV: 8.4±0.9 expected, 11 observed. • Fit mass distribution for Higgs Signal (MSSM scenario): • Exclude 140 GeV Higgs at 95% C.L. • Upper limit on cross section times branching ratio. Rick Field – Florida/CDF/CMS

  35. New since IMFP2006 Higgs → tt Search (CDF) events events No Significant Excess of events above SM background is observed! Rick Field – Florida/CDF/CMS

  36. W-boson Cross Section (CDF) W Acceptance • Extend electron coverage to the forward region (1.2 < |h| < 2.8)! IMFP2006 48,144 W candidates ~4.5% background overall efficiency of signal ~7% Rick Field – Florida/CDF/CMS

  37. New since IMFP2006 W-Boson Mass Measurement • The Challenge: • Do not know neutrino pz. • No full mass reconstruction possible. • Extract from a template fit to PT, MT, and Missing ET. • Transverse mass: MW = 80413 ± 48 MeV/c2 Single most precise measurement to date! Rick Field – Florida/CDF/CMS

  38. New since IMFP2006 W-Boson Width Measurement • Model transverse mass distribution over range 50-200 GeV. • Normalize 50-90 GeV and fit for the width in the high MT region 90-200 GeV. • The tail region is sensitive to the width of the Breit Wigner line-shape. Rick Field – Florida/CDF/CMS

  39. W+ W- y antiproton proton e+ u W+ p p d u e W Production Charge Asymmetry • There are more u-quarks than d-quarks at high x in the proton and hence the W+ (W-) is boosted in the direction of the incoming proton (antiproton). • Measuring the W± asymmetry constrains the PDF’s! Q2 = 100 GeV2 MRST2004NLO xG(x,Q2) u d d u x u 10-3 10-2 10-1 1 Rick Field – Florida/CDF/CMS

  40. New since IMFP2006 W Production Charge Asymmetry • Since the longitudinal momentum of the neutrino, pL(n), is not known the W rapidity cannot be reconstructed. • So previously one looked at the the electron charge asymmetry. • The V-A structure of the W+ (W-) decay favors a backward e+ (forward e-) which “dilutes” the W charge asymmetry! • New CDF measurement performed in W→en channel. • pL(n) is determined by constraining MW = 80.4 GeV leaving two possible yW solutions. Each solution receives a probability weight according to the V-A decay structure and the W cross-section, s(yW). • The process is iterated since s(yW) depends on the asymmetry. Rick Field – Florida/CDF/CMS

  41. W + g Cross Sections (CDF) IMFP2006 ET(g) > 7 GeV R(lg) > 0.7 Rick Field – Florida/CDF/CMS

  42. New since IMFP2006 W + g Cross Sections (CDF) ET(g) > 7 GeV R(lg) > 0.7 18.03±0.65(stat)±2.55(sys) ±1.05(lum) Rick Field – Florida/CDF/CMS

  43. Z + g Cross Sections (CDF) IMFP2006 Note: (W)/(Z) ≈ 4 while (W)/(Z) ≈ 11 ET(g) > 7 GeV R(lg) > 0.7 Rick Field – Florida/CDF/CMS

  44. New since IMFP2006 Z + g Cross Sections (CDF) 390 events ET(g) > 7 GeV R(lg) > 0.7 Meeg > 40 GeV/c2 Rick Field – Florida/CDF/CMS

  45. The W+W Cross-Section IMFP2006 Campbell & Ellis 1999 Rick Field – Florida/CDF/CMS

  46. The W+W Cross-Section (CDF) IMFP2006 L = 825 pb-1 We are beginning to study the details of Di-Boson production at the Tevatron! • WW→dileptons + MET • Two leptons pT > 20 GeV/c. • Z veto. • MET > 20 GeV. • Zero jets with ET>15 GeV and |h|<2.5. Observe 95 events with 37.2 background! Lepton-Pair Mass! Missing ET! ET Sum! Rick Field – Florida/CDF/CMS

  47. New since IMFP2006 WW+WZ Cross-Section NLO Theory σWW × Br(W→ln, W→jj) = 12.4 pb × 0.146 = 1.81 pb σWZ × Br(W→ln, Z→jj) = 3.96 pb × 0.07 = 0.28 pb Rick Field – Florida/CDF/CMS

  48. W+Z → trileptons + MET The Z+W, Z+Z Cross Sections IMFP2006 Observe 2 events with a background of 0.9±0.2! Upper Limits Rick Field – Florida/CDF/CMS

  49. New since IMFP2006 The W+Z Cross Section Strategy • Search for events with 3 leptons and missing energy. • Small cross-section but very clean signal. • Anomalous cross-section sensitive to non SM contributions. 3.0 σ significance! Rick Field – Florida/CDF/CMS

  50. New since IMFP2006 The Z+Z Cross Section Strategy: • Search for events with either 4 leptons or 2 leptons and significant missing ET. • Calculate a Prob(WW) or Prob(ZZ) based on event kinematics and LO cross section. • Construct a likelihood ratio. • Fit to extract the llnn signal. ZZ decaying into 2 leptons + MET ZZ decaying into 4 leptons 3.0 σ significance! Rick Field – Florida/CDF/CMS

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