Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 1 University of Chicago Rick Field University of Florida CDF Run 2 Enrico Fermi Institute, University of Chicago Lecture 2: Things I would Like to See Measured at the Tevatron Heavy Quarks, Bosons, & Photons

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 2 Heavy Quark & Boson Production at the Tevatron  Total inelastic  tot ~ 100 mb which is larger than the cross section for D-meson or a B-meson.  However there are lots of heavy quark events in 1 fb -1 !  Want to study the production of charmed mesons and baryons: D +, D 0, D s, c,  c,  c, etc.  Want to studey the production of B-mesons and baryons: B u, B d, B s, B c, b,  b, etc.  Two Heavy Quark Triggers at CDF: For semileptonic decays we trigger on  and e. For hadronic decays we trigger on one or more displaced tracks (i.e. large impact parameter). with 1 fb -1 ~1.4 x ~1 x ~6 x 10 6 ~6 x 10 5 ~14,000 ~5,000 CDF-SVT

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 3 Selecting Heavy Flavor Decays  To select charm and beauty in an hadronic environment requires: High resolution tracking A way to trigger on the hadronic decays (i.e. a way to trigger on tracks) CDF Primary Vertex Secondary Vertex I mpact P arameter ( ~100  m) L xy ~ 1 mm B/D decay D 0  K  The CDF Secondary Vertex Trigger (SVT) Online (L2) selection of displaced tracks based on Silicon detector hits.  At CDF we have a “Secondary Vertex Trigger” (the SVT). Collision Point

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 4 Selecting Prompt Charm Production  Separate prompt (i.e. direct) and secondary charm based on their transverse impact parameter distribution. Direct Charm Meson Fractions: D 0 : f D =86.4±0.4±3.5% D* + : f D =88.1±1.1±3.9% D + : f D =89.1±0.4±2.8% D + s : f D =77.3±3.8±2.1% B  D tail Prompt DSecondary D from B Prompt peak D impact parameter  Prompt D-meson decays point back to primary vertex (i.e. the collision point).  Secondary D-meson decays do not point back to the primary vertex. Most of reconstructed D mesons are prompt! Collision Point

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 5 Prompt Charm Meson Production  Theory calculation from M. Cacciari and P. Nason: Resummed perturbative QCD (FONLL), JHEP 0309,006 (2003). Fragmentation: ALEPH measurement, CTEQ6M PDF. Charm Meson P T Distributions CDF prompt charm cross section result published in PRL (hep-ex/ ) Data collected by SVT trigger from 2/2002-3/2002 L = 5.8±0.3 pb -1.

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 6 Comparisons with Theory  NLO calculations compatible within errors?  The p T shapes are consistent with the theory for the D mesons, but the measured cross section are a factor of about ~1.5 higher! Ratio of Data to Theory Next step is to study charm-anticharm correlations to learn about the contributions from different production mechanisms: “flavor creation” “flavor Excitation” “gluon splitting”

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 7 Bottom Quark Production at the Tevatron  Important to have good leading (or leading-log) order QCD Monte-Carlo model predictions of collider observables.  The leading-log QCD Monte-Carlo model estimates are the “base line” from which all other calculations can be compared.  If the leading-log order estimates are within a factor of two of the data, higher order calculations might be expected to improve the agreement.  If a leading-log order estimate is off by more than a factor of two, it usually means that one has overlooked something.  I see no reason why the QCD Monte-Carlo models should not qualitatively describe heavy quark production (in the same way they qualitatively describe light quark and gluon production). QCD Monte-Carlo leading order “Flavor Creation” is a factor of four below the data!  “Something is goofy” (Rick Field, CDF B Group Talk, December 3, 1999). Tevatron Run 1 b-Quark Cross Section Extrapolation of what is measured (i.e. B- mesons) to the parton level (i.e. b-quark)! CDF Run

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 8 Sources of Heavy Quarks  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). Leading Order Matrix Elements Leading-Log Order QCD Monte-Carlo Model (LLMC) (structure functions)× (matrix elements)× (Fragmentation) + (initial and final-state radiation: LLA)

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 9 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! Next to Leading Order Matrix Elements “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. Amp(gg→QQg) = ++  (gg→QQg) = 2 and there are interference terms!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 10 Inclusive b-quark Cross Section  Data on the integrated b-quark total cross section (P T > PTmin, |y| < 1) for proton-antiproton collisions at 1.8 TeV compared with the QCD Monte-Carlo model predictions of PYTHIA (CTEQ3L, PARP(67)=4). The four curves correspond to the contribution from “flavor creation”, “flavor excitation”, “gluon splitting”, and the resulting total. Total “Flavor Creation” “Flavor Excitation” “Gluon Splitting” Tevatron Run 1 b-Quark Cross Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 11 All three sources are important at the Tevatron! Conclusions from Run 1  All three sources are important at the Tevatron and the QCD leading-log Monte-Carlo models do a fairly good job in describing the majority of the b-quark data at the Tevatron.  We should be able experimentally to isolate the individual contributions to b-quark production by studying b-bbar correlations find out in much greater detail how well the QCD Monte-Carlo models actually describe the data.  One has to be very careful when the experimenters extrapolate to the parton level and publish parton level results. The parton level is not an observable! Experiments measure hadrons! To extrapolate to the parton level requires making additional assumptions that may or may not be correct (and often the assumptions are not clearly stated or are very complicated). It is important that the experimenters always publish the corresponding hadron level result along with their parton level extrapolation.  One also has to be very careful when theorists attempt to compare parton level calculations with experimental data. Hadronization and initial/final-state radiation effects are almost always important and theorists should embed their parton level results within a parton-shower/hadronization framework (e.g. HERWIG or PYTHIA). “Nothing is goofy” Rick Field, Cambridge Workshop, July 18, 2002

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 12 The Run 2 J/  Cross Section  The J/  inclusive cross-section includes contribution from the direct production of J/  and from decays from excited charmonium,  (2S), and from the decays of b- hadrons, B→ J/  + X. CDF (  b)  (J/  |Y(J/  )| < 0.6)4.08  0.02(stat)+0.36(sys)-0.48(sys) Down to P T = 0! J/  K B   J/  coming from b-hadrons will be displaced from primary vertex! 39.7 pb -1 Primary vertex (i.e. interaction point)

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 13  Run 2 B-hadron P T distribution compared with FONLL (CTEQ6M). B-hadron p T CDF (  b)FONLL (  b)  (B-hadron)29.4  0.6(stat)  6.2(sys) |Y| < 1.0  Good agreement between theory and experiment! 39.7 pb -1 Cacciari, Frixone, Mangano, Nason, Ridolfi PRD 71, (2005) CDF Run 2 B-hadron Cross Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 14  b-quark tag based on displaced vertices. Secondary vertex mass discriminates flavor.  Require one secondary vertex tagged b-jet within 0.1 < |y|< 0.7 and plot the inclusive jet P T distribution (MidPoint, R = 0.7). Collision point CDF Run 2 b-Jet Cross Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 15  Shows the CDF inclusive b-jet cross section (MidPoint, R = 0.7, f merge = 0.75) at 1.96 TeV with L = 300 pb -1.  Shows data/theory for NLO (with large scale uncertainties).  Shows data/theory for PYTHIA Tune A. CDF Run 2 b-Jet Cross Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 16 The b-bbar DiJet Cross-Section  E T (b-jet#1) > 30 GeV, E T (b-jet#2) > 20 GeV, |  (b-jets)| < 1.2. Differential Cross Section as a function of the b-bbar DiJet invariant mass! Preliminary CDF Results:  bb = 34.5  1.8  10.5 nb QCD Monte-Carlo Predictions: PYTHIA Tune A CTEQ5L ± 0.62 nb HERWIG CTEQ5L21.53 ± 0.66 nb ± 0.58 nb Predominately Flavor creation! Systematic Uncertainty  Large Systematic Uncertainty:  Jet Energy Scale (~20%).  b-tagging Efficiency (~8%)

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 17 The b-bbar DiJet Cross-Section  E T (b-jet#1) > 30 GeV, E T (b-jet#2) > 20 GeV, |  (b-jets)| < 1.2. Preliminary CDF Results:  bb = 34.5  1.8  10.5 nb QCD Monte-Carlo Predictions: PYTHIA Tune A CTEQ5L 38.7 ± 0.6 nb HERWIG CTEQ5L21.5 ± 0.7 nb ± 0.6 nb + Jimmy35.7 ± 2.0 nb Differential Cross Section as a function of the b-bbar DiJet invariant mass! Adding multiple parton interactions (i.e. JIMMY) to enhance the “underlying event” increases the b-bbar jet cross section! JIMMY: MPI J. M. Butterworth J. R. Forshaw M. H. Seymour JIMMY Runs with HERWIG and adds multiple parton interactions!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 18 b-bbar DiJet Correlations  The two b-jets are predominately “back-to- back” (i.e. “flavor creation”)!  Pythia Tune A agrees fairly well with the  correlation! Differential Cross Section as a function of  of the two b-jets! Tune A! Not an accident!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 19 Top Decay Channels  m t >m W +m b so dominant decay t  Wb.  The top decays before it hadronizes.  B(W  qq) ~ 67%.  B(W  l ) ~ 11% l = e, 

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 20 Dilepton Channel  Backgrounds: Physics: Drell-Yan, WW/WZ/ZZ, Z   Instrumental: fake lepton  Selection: 2 leptons E T > 20 GeV with opposite sign. >=2 jets E T > 15 GeV. Missing E T > 25 GeV (and away from any jet). H T =p Tlep +E Tjet +ME T > 200 GeV. Z rejection.  (tt) = 8.3 ± 1.5 (stat) ± 1.0 (syst) (lumi) pb 65 events 20 events background

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 21 Lepton+Jets Channel Kinematics  Selection: 1 lepton with p T > 20 GeV/c. >= 3 jets with p T > 15GeV/c. Missing E T > 20 GeV.  Backgrounds: W+jets QCD spherical central binned likelihood fit  Use 7 kinematic variables in neural net to discriminate signal from background! One of the 7 variables!  (tt) = 6.0 ± 0.6 (stat) ± 0.9 (syst) pb Neural net output!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 22 Lepton+Jets Channel H T >200GeV 2 b tags b-Tagging  Require b-jet to be tagged for discrimination. Tagging efficiency for b jets~50% for c jets~10% for light q jets < 0.1% 1 b tag ~150 events Small background!  (tt) = 8.2 ± 0.6 (stat) ± 1.1 (syst) pb ~45 events

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 23 Tevatron Top-Pair Cross-Section Bonciani et al., Nucl. Phys. B529, 424 (1998) Kidonakis and Vogt, Phys. Rev. D68, (2003) Theory CDF Run 2 Preliminary

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 24 CDF M top Results CDF Lepton+jets: M top (template) = ± 2.5 (stat. + jet E) ± 1.3 (syst.) GeV M top (matrix element) = ± 2.5 (stat. + jet E) ± 1.4 (syst.) GeV M top (L xy ) = (stat.) ± 5.6 (syst.) GeV CDF Dilepton: M top (matrix element) = ± 4.5 (stat.) ± 3.1 (jet E. + syst.) GeV Transverse decay length!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 25 Top Quark Mass Summer 2005 Dilepton: CDF-II M top ME = ± 5.5 GeV Lepton+Jets: CDF-II M top Temp = ± 2.8 GeV CDF-II M top ME = ± 2.9 GeV CDF Combined: M top CDF = ± 1.6 ± 2.2 GeV = ± 2.7 GeV New since Summer 2005

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 26 Top Cross-Section vs Mass Tevatron Summer 2005CDF Winter 2006 Updated CDF+DØ combined result is coming soon! CDF combined

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 27 Is Anything “Goofy”?  Possible discrepancy between l + jets and the dilepton channel measurements of the top mass??  Is it statistical? Unlikely!  Is there a missing systematic?  This is probably nothing, but we should keep an eye on it!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 28 Future Top Mass Measurements  Expect significant reduction in jet energy scale uncertainty with more data.  Today we have CDF-II M top (Temp) = ± 2.8 GeV (~0.7 fb -1 ).  CDF should be able to achieve 1.5 GeV uncertainty on top mass! Systematic Source Uncertainty (GeV/c 2 ) ISR/FSR0.7 Model0.7 b-jet0.6 Method0.6 PDF0.3 Total1.3 Jet Energy2.5

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 29 Constraining the Higgs Mass  Top quark mass is a fundamental parameter of SM.  Radiative corrections to SM predictions dominated by top mass.  Top mass together with W mass places a constraint on Higgs mass! Tevatron Run I + LEP2 Spring 2006 Summer 05 Light Higgs very interesting for the Tevatron!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 30 DØ Prelim. 365 pb -1 Top Charge  top < 1.75x s c  top < 52.5  m at 95%CL Exclude |Q| = 4/3 at 94% CL Reconstructed Top Charge (e) SM bgrnd signal f + (DØ combined) = 0.04 ± 0.11(stat) ± 0.06(syst) f + (SM pred.) = 0 signal+bgrnd 370 pb -1 hep-ex/ CDF Prelim. 318 pb -1 Top Lifetime Impact Parameter (  m) Everything consistent with the Standard Model (so far)! Top: Charge, Branching, Lifetime, W Helicity

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 31 Other Sources of Top Quarks ~85% g g Strongly Produced tt Pairs  Dominant production mode  NLO+NLL = 6.7  1.2 pb  Relatively clean signature  Discovery in 1995 ElectroWeak Production: Single Top  Larger background  Smaller cross section  ≈ 2 pb  Not yet observed! ~15%

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 32 Single Top Production s-channelt-channelAssociated tW Combine (s+t) Tevatron  NLO 0.88  0.11 pb1.98  0.25 pb ~ 0.1 pb LHC  NLO 10.6  1.1 pb247  25 pb pb CDF< 18 pb< 13 pb< 14 pb D0< 17 pb< 22 pb B.W. Harris et al.:Phys.Rev.D66, T.Tait: hep-ph/ Z.Sullivan Phys.Rev.D70: Belyaev,Boos: hep-ph/ Run I 95% C.L. (m top =175 GeV/c 2 ) s-channelt-channel tW associated production

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 33 Single Top Results from CDF  To the network 2D output, CDF applies a maximum likelihood fit and the best fits for t and s-channels are: t-channel:  < % C.L. s-channel:  < % C.L. The CDF limits!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 34 Single Top at the Tevatron  The current CDF and DØ analyses not only provide drastically improved limits on the single top cross-section, but set all necessary tools and methods toward a possible discovery with a larger data sample!  Both collaborations are aggressively working on improving the results! 95% C.L. limits on single top cross-section We should see single top soon !!! Channel CDF (696 pb -1 ) DØ (370 pb -1 ) Combined3.4 pb s-channel3.2 pb5.0 pb t-channel3.1 pb4.4 pb (2 pb) (0.9 pb) (2.9 pb) Theory!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 35 Top-AntiTop Resonances  CDF observed an intriguing excess of events with top-antitop invariant mass around 500 GeV! Phys.Rev.Lett. 85, 2062 (2000) CDF Run 1 Excess is reduced!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 36 Direct Photon Cross-Section  DØ uses a neural network (NN) with track isolation and calorimeter shower shape variables to separate direct photons from background photons and  0 ’s!  g q q Highest p T (  ) is 442 GeV/c (3 events above 300 GeV/c not displayed)! Note rise at low p T !

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 37  b/c-quark tag based on displaced vertices. Secondary vertex mass discriminates flavor. L = 67 pb -1  + b/c Cross Sections

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 38  PYTHIA Tune A correctly predicts the relative amount of u, d, s, c, b quarks within the photon events. CDF (pb)  (b+  40.6  19.5(stat)+7.4(sys)-7.8(sys)  (c+   152.9(stat)+86.5(sys)-90.9(sys)  + c  + b  T (  ) > 25 GeV L = 67 pb -1 PYTHIA Tune A!  + b/c Cross Sections

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 39  Di-Photon cross section with 207 pb -1 of Run 2 data compared with next-to- leading order QCD predictions from DIPHOX and ResBos.  +  mass  +   L = 207 pb -1 QCD  +   +  Cross Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 40  Impressive agreement between experiment and NNLO theory (Stirling, van Neerven)! CDF (pb)NNLO (pb)  (Z→e + e - )254.9  3.3(stat)  4.6(sys)  15.2(lum)252.3  5.0 L = 72 pb -1 QCD Drell-Yan Z-boson Cross Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 41 Z-boson Cross Section  Impressive agreement between experiment and NNLO theory (Stirling, van Neerven)! CDF (pb)NNLO (pb)  (Z→  +  - )261.2  2.7(stat)  6.9(sys)  15.1(lum)252.3  5.0 L = 337 pb -1

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 42 The Z→  Cross Section Signal cone Isolation cone  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). π 0 detected by the CES detector and required to be in the signal cone.  CES: resolution 2-3mm, proportional strip/wire drift chamber at 6X 0 of EM calorimeter.  Channel for Z→ττ: electron + isolated track One  decays to an electron: τ→e+X (E T (e) > 10 GeV). One  decays to hadrons: τ → h+X (p T > 15GeV/c).  Remove Drell-Yan e + e - and apply event topology cuts for non-Z background.

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 43 The Z→  Cross Section  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%! 1 and 3 tracks, opposite sign same sign, opposite sign CDF (pb)NNLO (pb)  (Z→  +  - )265  20(stat)  21(sys)  15(lum)252.3  5.0

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 44 Higgs →  Search  Data mass distribution agrees with SM expectation: M H > 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. 140 GeV Higgs Signal! events 1 event Let’s find the Higgs!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 45  (W) L CDF (pb)NNLO(pb) Central electrons 72 pb  10(stat)  53(sys)  167(lum)2687  54 Forward electrons 223 pb  13(stat)  94(sys)  169(lum)2687  54 CDFNNLO  (W)/  (Z)10.92  0.15(stat)  0.14(sys)10.69  0.08  Extend electron coverage to the forward region (1.2 < |  | < 2.8)! 48,144 W candidates ~4.5% background overall efficiency of signal ~7% W-boson Cross Section W Acceptance

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage Years of Measuring W & Z

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 47 Z + b-Jet Production  Important background for new physics! Extract fraction of b-tagged jets from secondary vertex mass distribution: NO assumption on the charm content. L = 335 pb -1 CDF Assumption on the charm content from theoretical prediction: N c =1.69N b. DØDØ Agreement with NLO prediction:  Leptonic decays for the Z.  Z associated with jets.  CDF: JETCLU, D0: MidPoint:  R = 0.7, |  jet | 20 GeV  Look for tagged jets in Z events. L = 180 pb -1

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 48 W +  Cross Sections CDF (pb)NLO (pb)  (W+  )*B R (W->l )19.7  1.7(stat)  2.0(sys)  1.1(lum)19.3  1.4 E T (  ) > 7 GeV R(l  ) > 0.7

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 49 Z +  Cross Sections CDF (pb)NLO (pb)  (Z+  )*B R (Z->ll)5.3  0.6(stat)  0.3(sys)  0.3(lum)5.4  0.3 E T (  ) > 7 GeV R(l  ) > 0.7 Note:  (W  )/  (Z  ) ≈ 4 while  (W)/  (Z) ≈ 11

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 50 pb -1 CDF (pb)NLO (pb)  (WW) CDF (stat)-5.1(stat)  1.8(sys)  0.9(lum)12.4  0.8  (WW) DØ (stat)-3.8(stat)  1.2(sys)  0.9(lum)12.4  0.8 Campbell & Ellis 1999 W+W Cross-Section

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 51 W+W Cross-Section L CDF (pb)NLO (pb)  (WW) 825 pb  2.3(stat)  1.6(sys)  1.2(lum)12.4  0.8  WW→dileptons + MET  Two leptons p T > 20 GeV/c.  Z veto.  MET > 20 GeV.  Zero jets with E T >15 GeV and |  |<2.5. Observe 95 events with 37.2 background! L = 825 pb -1 Missing ET!Lepton-Pair Mass! ET Sum! We are beginning to study the details of Di-Boson production at the Tevatron!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 52 W+Z, Z+ZLimit (pb)NLO (pb) CDF (194 pb -1 ) sum < 15.2 (95% CL) 5.0  0.4 DØ (300 pb -1 ) W+Z < 13.3 (95% CL) 3.7  0.1 Upper Limits CDF (825 pb -1 ) W+Z < 6.34 (95% CL) 3.7  0.1 W+Z → trileptons + MET Observe 2 events with a background of 0.9±0.2! Z+W, Z+Z Cross Sections

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 53 Di-Bosons at the Tevatron We are getting closer to the Higgs! W Z W+  Z+  W+W W+Z

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 54 Generic Squark & Gluino Search  Selection:  3 jets with E T >125 GeV, 75 GeV and 25 GeV.  Missing E T >165 GeV.  H T =∑ jet E T > 350 GeV.  Missing E T not along a jet direction: Avoid jet mismeasurements.  Background:  W/Z+jets with W  l or Z .  Top.  QCD multijets: Mismeasured jet energies lead to missing E T.  Observe: 3, Expect: 4.1±1.5. PYTHIA Tune A It will be a long time before ATLAS & CMS understand their missing E T spectrum this well!

Lecture 2: University of Chicago July 10, 2006 Rick Field – Florida/CDFPage 55 Future Higgs & SUSY Searches  CDF and Tevatron running great!  Often world’s best constraints.  Many searches on SUSY, Higgs and other new particles.  Most current analyses based on up to 350 pb -1 :  We will analyze 1 fb -1 by summer  Anticipate fb -1 by  The Tevatron has a chance of finding new physics before the ATLAS and CMS understand their dectors!  We may be able to tell the LHC where to look! If we find something the real fun starts: What Is It? Let’s find the Higgs!