XXXIV International Meeting on Fundamental Physics

1. Physics at the Tevatron XXXIV International Meeting on Fundamental Physics From HERA and the TEVATRON to the LHC Rick Field University of Florida (for the CDF & D0 Collaborations) Real Colegio Maria Cristina, El Escorial, Spain 2nd Lecture Heavy Quark Physics at the Tevatron CDF Run 2 Rick Field – Florida/CDF/CMS

2. Heavy Quark Physics at the Tevatron • Charm Production at the Tevatron. • J/Y and Bottom Production at the Tevatron. • Top Production at the Tevatron. Rick Field – Florida/CDF/CMS

3. Heavy Quark Production at the Tevatron • Total inelastic stot ~ 100 mb which is 103-104 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+, D0, Ds , lc , cc , Xc, etc. • Want to studey the production of B-mesons and baryons: Bu , Bd , Bs , Bc , lb , Xb, etc. with 1 fb-1 ~1.4 x 1014 ~1 x 1011 ~6 x 106 ~6 x 105 ~14,000 ~5,000 • Two Heavy Quark Triggers at CDF: • For semileptonic decays we trigger on m and e. • For hadronic decays we trigger on one or more displaced tracks (i.e. large impact parameter). CDF-SVT Rick Field – Florida/CDF/CMS

4. Lxy ~ 1 mm B/D decay Primary Vertex Secondary Vertex CDF Impact Parameter( ~100mm) D0 K 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) • At CDF we have a “Secondary Vertex Trigger” (the SVT). The CDFSecondary Vertex Trigger (SVT) • Online (L2) selection of displaced tracks based on Silicon detector hits. Collision Point Rick Field – Florida/CDF/CMS

5. Selecting Prompt Charm Production Collision Point • Separate prompt (i.e. direct) and secondary charm based on their transverse impact parameter distribution. Prompt D Secondary D from B • 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. Prompt peak Direct Charm Meson Fractions: D0: fD=86.4±0.4±3.5% D*+: fD=88.1±1.1±3.9% D+: fD=89.1±0.4±2.8% D+s: fD=77.3±3.8±2.1% BD tail D impact parameter Most of reconstructed D mesons are prompt! Rick Field – Florida/CDF/CMS

6. Prompt Charm Meson Production Charm Meson PT Distributions • Theory calculation from M. Cacciari and P. Nason: Resummed perturbative QCD (FONLL), JHEP 0309,006 (2003). Fragmentation: ALEPH measurement, CTEQ6M PDF. CDF prompt charm cross section result published in PRL (hep-ex/0307080) Data collected by SVT trigger from 2/2002-3/2002 L = 5.8±0.3 pb-1. Rick Field – Florida/CDF/CMS

7. Comparisons with Theory • NLO calculations compatible within errors? • The pT shapes are consistent with the theory for the D mesons, but the measured cross section are a factor of about ~1.5 higher! Next step is to study charm-anticharm correlations to learn about the contributions from different production mechanisms: “flavor creation” “flavor Excitation” “gluon splitting” Ratio of Data to Theory Rick Field – Florida/CDF/CMS

8. 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). CDF Run 1 1999 Tevatron Run 1 b-Quark Cross Section QCD Monte-Carlo leading order “Flavor Creation” is a factor of four below the data! Extrapolation of what is measured (i.e. B-mesons) to the parton level (i.e. b-quark)! • “Something is goofy” (Rick Field, CDF B Group Talk, December 3, 1999). Rick Field – Florida/CDF/CMS

9. The Sources of Heavy Quarks Leading-Log Order QCD Monte-Carlo Model (LLMC) • 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 (structure functions) × (matrix elements) × (Fragmentation) + (initial and final-state radiation: LLA) Rick Field – Florida/CDF/CMS

10. 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

11. Inclusive b-quark Cross Section • Data on the integrated b-quark total cross section (PT > PTmin, |y| < 1) for proton-antiproton collisions at 1.8 TeV compared with the QCD Monte-Carlo model predictions of PYTHIA 6.158 (CTEQ3L, PARP(67)=4). The four curves correspond to the contribution from “flavor creation”, “flavor excitation”, “gluon splitting”, and the resulting total. Tevatron Run 1 b-Quark Cross Section Total “Flavor Excitation” “Flavor Creation” “Gluon Splitting” Rick Field – Florida/CDF/CMS

12. 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 correlationsfind 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 All three sources are important at the Tevatron! MC@NLO! Rick Field – Florida/CDF/CMS

13. PT Asymmetry • Predictions of PYTHIA 6.158 (CTEQ4L, PARP(67)=1) for the asymmetry A = (PT1-PT2)/(PT1+PT2) for events with a b-quark with PT1 > 0 GeV/c and |y1| < 1.0 and a bbar quark with PT2 > 5 GeV/c and |y2| < 1.0 in proton-antiproton collisions at 1.8 TeV. The curves correspond to ds/dA (mb) for flavor creation, flavor excitation, shower/fragmentation, and the resulting total. “Flavor Excitation” “Flavor Creation” “Gluon Splitting” Rick Field – Florida/CDF/CMS

14. Distance R in h-f Space • Predictions of PYTHIA 6.158 (CTEQ4L, PARP(67)=1) for the distance, R, in h-f space between the b and bbar-quark with |y1|<1 and |y2|<1 in proton-antiproton collisions at 1.8 TeV. The curves correspond to ds/dR (mb) for flavor creation, flavor excitation, shower/fragmentation, and the resulting total. “Gluon Splitting” Rick Field – Florida/CDF/CMS

15. Azimuthal Correlations “Flavor Creation” • Predictions of PYTHIA 6.206 (CTEQ5L) with PARP(67)=1 (new default) and PARP(67)=4 (old default) for the azimuthal angle, Df, between a b-quark with PT1 > 15 GeV/c, |y1| < 1 and bbar-quark with PT2 > 10 GeV/c, |y2|<1 in proton-antiproton collisions at 1.8 TeV. The curves correspond to ds/dDf (mb/o) for flavor creation, flavor excitation, gluon splitting, and the resulting total. Old PYTHIA default (more initial-state radiation) New PYTHIA default (less initial-state radiation) “Flavor Excitation” “Gluon Splitting” Rick Field – Florida/CDF/CMS

16. Azimuthal Correlations Old PYTHIA default (more initial-state radiation) • Predictions of HERWIG 6.4 (CTEQ5L) for the azimuthal angle, Df, between a b-quark with PT1 > 15 GeV/c, |y1| < 1 and bbar-quark with PT2 > 10 GeV/c, |y2|<1 in proton-antiproton collisions at 1.8 TeV. The curves correspond to ds/dDf (mb/o) for flavor creation, flavor excitation, shower/fragmentation, and the resulting total. New PYTHIA default (less initial-state radiation) “Flavor Creation” Rick Field – Florida/CDF/CMS

17. CDF Run I AnalysisAzimuthal Correlations • Run I CDF data for the azimuthal angle, Df, between a b-quark |y1| < 1 and bbar-quark |y2|<1 in proton-antiproton collisions at 1.8 TeV favored PYTHIA Tune A (PARP(67) = 4). Kevin Lannon DPF2002 Now published! Rick Field – Florida/CDF/CMS

18. J/   B K The Run 2 J/Y Cross Section • The J/y inclusive cross-section includes contribution from the direct production of J/y and from decays from excited charmonium, Y(2S), and from the decays of b-hadrons, B→ J/y + X. 4.8 pb-1 J/y coming from b-hadrons will be displaced from primary vertex! Down to PT = 0! 39.7 pb-1 Primary vertex (i.e. interaction point) Rick Field – Florida/CDF/CMS

19. CDF Run 2 B-hadron Cross Section PRD 71, 032001 (2005) • Run 2 B-hadron PT distribution compared with FONLL (CTEQ6M). Cacciari, Frixone, Mangano, Nason, Ridolfi • Good agreement between theory and experiment! 39.7 pb-1 |Y| < 1.0 B-hadron pT Rick Field – Florida/CDF/CMS

20. CDF Run 2 b-Jet Cross Section Collision point • 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 PT distribution (MidPoint, R = 0.7). Rick Field – Florida/CDF/CMS

21. CDF Run 2 b-Jet Cross Section • Shows the CDF inclusive b-jet cross section (MidPoint, R = 0.7, fmerge = 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. Rick Field – Florida/CDF/CMS

22. The b-bbar DiJet Cross-Section • ET(b-jet#1) > 30 GeV, ET(b-jet#2) > 20 GeV, |h(b-jets)| < 1.2. Systematic Uncertainty Preliminary CDF Results: sbb = 34.5  1.8  10.5nb QCD Monte-Carlo Predictions: Differential Cross Section as a function of the b-bbar DiJet invariant mass! • Large Systematic Uncertainty: • Jet Energy Scale (~20%). • b-tagging Efficiency (~8%) Predominately Flavor creation! Rick Field – Florida/CDF/CMS

23. “Flavor Creation” b-quark Initial - State Radiation Proton AntiProton Underlying Event Underlying Event Final - State b-quark Radiation The b-bbar DiJet Cross-Section • ET(b-jet#1) > 30 GeV, ET(b-jet#2) > 20 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

24. b-bbar DiJet Correlations Tune A! Differential Cross Section as a function of Df of the two b-jets! • The two b-jets are predominately “back-to-back” (i.e. “flavor creation”)! • Pythia Tune A agrees fairly well with the Df correlation! Not an accident! Rick Field – Florida/CDF/CMS

25. Top Production at the Tevatron • Top quark discovered in 1995 by CDF and DØ. • Not a surprise: SM quark sector now complete. • Now study the detailed properties of the top: • Charge. • Lifetime. • Branching ratios. • W-boson helicity. • Make precision measurements: • Cross-sections now 12%! • Mass now 2%! • Measure single top production! Rick Field – Florida/CDF/CMS

26. Top Decay Channels • mt>mW+mb so dominant decay tWb. • The top decays before it hadronizes. • B(W  qq) ~ 67%. • B(W ln) ~ 11% l = e, m, t. Rick Field – Florida/CDF/CMS

27. s(tt) =  8.3 ± 1.5 (stat) ± 1.0 (syst) + 0.5 (lumi) pb Dilepton Channel (CDF) • Backgrounds: • Physics: Drell-Yan, WW/WZ/ZZ, Z tt • Instrumental: fake lepton • Selection: • 2 leptons ET > 20 GeV with opposite sign. • >=2 jets ET > 15 GeV. • Missing ET > 25 GeV (and away from any jet). • HT=pTlep+ETjet+MET > 200 GeV. • Z rejection. New 65 events 20 events background Rick Field – Florida/CDF/CMS

28. s(tt) =  6.0 ± 0.6 (stat) ± 0.9 (syst) pb Lepton+Jets Channel (CDF) Kinematics • Backgrounds: • W+jets • QCD • Selection: • 1 lepton with pT > 20 GeV/c. • >= 3 jets with pT > 15GeV/c. • Missing ET > 20 GeV. central • Use 7 kinematic variables in neural net to discriminate signal from background! One of the 7 variables! spherical New binned likelihood fit Neural net output! Rick Field – Florida/CDF/CMS

29. s(tt) =  8.2 ± 0.6 (stat) ± 1.1 (syst) pb Lepton+Jets Channel (CDF) b-Tagging • Require b-jet to be tagged for discrimination. 1 b tag Tagging efficiency for b jets~50% for c jets~10% for light q jets < 0.1% New 2 b tags HT>200GeV ~150 events ~45 events Small background! Rick Field – Florida/CDF/CMS

30. All Hadronic Channel (DØ) • Huge QCD background! • Selection: • >=6 jets with pT > 15 GeV/c. • >=1 b tagged. • NN discriminant > 0.9. • Use 6 kinematic variables in neural net to discriminate signal from background! Geometric mean of 5th and 6th leading jet ET One of the 6 variables! Rick Field – Florida/CDF/CMS

31. Tevatron Top-Pair Cross Section CDF Run 2 Preliminary Theory Bonciani et al., Nucl. Phys. B529, 424 (1998) Kidonakis and Vogt, Phys. Rev. D68, 114014 (2003) Rick Field – Florida/CDF/CMS

32. New CDF Mtop Results Transverse decay length! CDF Lepton+jets: Mtop (template) = 173.4 ± 2.5 (stat. + jet E) ± 1.3 (syst.) GeV Mtop (matrix element) = 174.1 ± 2.5 (stat. + jet E) ± 1.4 (syst.) GeV Mtop (Lxy) = 183.9 +15.7-13.9 (stat.) ± 5.6 (syst.) GeV CDF Dilepton: Mtop (matrix element) = 164.5 ± 4.5 (stat.) ± 3.1 (jet E. + syst.) GeV Rick Field – Florida/CDF/CMS

33. Top Quark Mass Summer 2005 New since Summer 2005 Dilepton: CDF-II MtopME = 164.5 ± 5.5 GeV Lepton+Jets: CDF-II MtopTemp = 174.1 ± 2.8 GeV CDF-II MtopME = 173.4 ± 2.9 GeV CDF Combined: MtopCDF = 172.0 ± 1.6 ± 2.2 GeV = 172.0 ± 2.7 GeV Rick Field – Florida/CDF/CMS

34. Top Cross-Section vs Mass Tevatron Summer 2005 CDF Winter 2006 CDF combined Updated CDF+DØ combined result is coming soon! Rick Field – Florida/CDF/CMS

35. Is Anything “Goofy”? • Possible discrepancy between l + jets and the dilepton channel measurements of the top mass?? • Is it statistical? • ME(dilepton) vs Templ(l+jets):c2 = 2.9/1, Prob = 0.09 (accounts for correlated systematics). • Is there a missing systematic? • This is probably nothing, but we should keep an eye on it! Rick Field – Florida/CDF/CMS

36. Future Top Mass Measurements • Expect significant reduction in jet energy scale uncertainty with more data. • Today we have CDF-II Mtop(Temp) = 174.1 ± 2.8 GeV (~0.7 fb-1). • CDF should be able to achieve 1.5 GeV uncertainty on top mass! Rick Field – Florida/CDF/CMS

37. Tevatron Run I + LEP2 This spring? 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! Summer 05 114 GeV Higgs very interesting for the Tevatron! Rick Field – Florida/CDF/CMS

38. Top: Charge, Branching, Lifetime, W Helicity Top Lifetime Top Charge CDF Prelim. 318 pb-1 DØ Prelim. 365 pb-1 Everything consistent with the Standard Model! top< 1.75x10-13s ctop< 52.5m at 95%CL Exclude |Q| = 4/3 at 94% CL Reconstructed Top Charge (e) Impact Parameter (m) 370 pb-1 f+ (DØ combined) = 0.04 ± 0.11(stat) ± 0.06(syst) f+ (SM pred.) = 0 SM signal signal+bgrnd hep-ex/0603002 bgrnd Rick Field – Florida/CDF/CMS

39. Strongly Produced tt Pairs g g Other Sources of Top Quarks • Dominant production mode NLO+NLL = 6.7  1.2 pb • Relatively clean signature • Discovery in 1995 ~85% ~15% ElectroWeak Production: Single Top • Larger background • Smaller cross section s≈ 2 pb • Not yet observed! Rick Field – Florida/CDF/CMS

40. Single Top Production tW associated production s-channel t-channel (mtop=175 GeV/c2) Run I 95% C.L. B.W. Harris et al.:Phys.Rev.D66,054024 T.Tait: hep-ph/9909352 Z.Sullivan Phys.Rev.D70:114012 Belyaev,Boos: hep-ph/0003260 Rick Field – Florida/CDF/CMS

41. New 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: The new CDF limits! t-channel:  < 3.1 pb @ 95% C.L. s-channel:  < 3.2 pb @ 95% C.L. Rick Field – Florida/CDF/CMS

42. Single Top at the Tevatron 95% C.L. limits on single top cross-section (2.9 pb) (0.9 pb) (2 pb) • 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! Theory! Single Top Discovery is Possible in Run 2 !!!! Rick Field – Florida/CDF/CMS

43. Top-AntiTop Resonances CDF Run 1 Excess is reduced! Phys.Rev.Lett. 85, 2062 (2000) • CDF observed an intriguing excess of events with top-antitop invariant mass around 500 GeV! Rick Field – Florida/CDF/CMS