XXXVI International Meeting on Fundamental Physics

1. Physics at the Tevatron XXXVI International Meeting on Fundamental Physics From IMFP2006 → IMFP2008 Rick Field University of Florida (for the CDF & D0 Collaborations) 1st Lecture FF Phenomenology → Tevatron Jet Physics Palacio de Jabalquinto, Baeza, Spain CDF Run 2 Rick Field – Florida/CDF/CMS

2. The Fermilab Tevatron • Fermi National Laboratory (Fermilab) is near Chicago, Illinois. CDF and DØ are the the two collider detector experiments at Fermilab. • Protons collide with antiprotons at a center-of-mass energy of almost2 TeV (actually 1.96 TeV). Rick Field – Florida/CDF/CMS

3. 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

4. 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

5. ~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

6. Feynman-Field Phenomenology Toward and Understanding of Hadron-Hadron Collisions 1st hat! Feynman and Field • From 7 GeV/c p0’s to 600 GeV/c Jets. The early days of trying to understand and simulate hadron-hadron collisions. Rick Field – Florida/CDF/CMS

7. Hadron-Hadron Collisions Field-Feynman 1977 (preQCD) • What happens when two hadrons collide at high energy? Feynman quote from FF1 “The model we shall choose is not a popular one, so that we will not duplicate too much of the work of others who are similarly analyzing various models (e.g. constituent interchange model, multiperipheral models, etc.). We shall assume that the high PT particles arise from direct hard collisions between constituent quarks in the incoming particles, which fragment or cascade down into several hadrons.” • Most of the time the hadrons ooze through each other and fall apart (i.e.no hard scattering). The outgoing particles continue in roughly the same direction as initial proton and antiproton. • Occasionally there will be a large transverse momentum meson. Question: Where did it come from? • We assumed it came from quark-quark elastic scattering, but we did not know how to calculate it! “Black-Box Model” Rick Field – Florida/CDF/CMS

8. Quark-Quark Black-Box Model No gluons! FF1 1977 (preQCD) Quark Distribution Functions determined from deep-inelastic lepton-hadron collisions Feynman quote from FF1 “Because of the incomplete knowledge of our functions some things can be predicted with more certainty than others. Those experimental results that are not well predicted can be “used up” to determine these functions in greater detail to permit better predictions of further experiments. Our papers will be a bit long because we wish to discuss this interplay in detail.” Quark Fragmentation Functions determined from e+e- annihilations Quark-Quark Cross-Section Unknown! Deteremined from hadron-hadron collisions. Rick Field – Florida/CDF/CMS

9. Quark-Quark Black-Box Model Field-Feynman 1977 (preQCD) Predict increase with increasing CM energy W Predict particle ratios “Beam-Beam Remnants” Predict overall event topology (FFF1 paper 1977) 7 GeV/c p0’s! Rick Field – Florida/CDF/CMS

10. Feynman Talk at Coral Gables(December 1976) 1st transparency Last transparency “Feynman-Field Jet Model” Rick Field – Florida/CDF/CMS

11. QCD Approach: Quarks & Gluons Quark & Gluon Fragmentation Functions Q2 dependence predicted from QCD FFF2 1978 Feynman quote from FFF2 “We investigate whether the present experimental behavior of mesons with large transverse momentum in hadron-hadron collisions is consistent with the theory of quantum-chromodynamics (QCD) with asymptotic freedom, at least as the theory is now partially understood.” Parton Distribution Functions Q2 dependence predicted from QCD Quark & Gluon Cross-Sections Calculated from QCD Rick Field – Florida/CDF/CMS

12. High PT Jets CDF (2006) Feynman, Field, & Fox (1978) Predict large “jet” cross-section 30 GeV/c! Feynman quote from FFF “At the time of this writing, there is still no sharp quantitative test of QCD. An important test will come in connection with the phenomena of high PT discussed here.” 600 GeV/c Jets! Rick Field – Florida/CDF/CMS

13. “Hard Scattering” Component QCD Monte-Carlo Models:High Transverse Momentum Jets • Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and final-state gluon radiation (in the leading log approximation or modified leading log approximation). “Underlying Event” • The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or semi-soft multiple parton interactions (MPI). The “underlying event” is an unavoidable background to most collider observables and having good understand of it leads to more precise collider measurements! • Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event” observables receive contributions from initial and final-state radiation. Rick Field – Florida/CDF/CMS

14. Collider Coordinates • The z-axis is defined to be the beam axis with the xy-plane being the “transverse” plane. • qcm is the center-of-mass scattering angle and f is the azimuthal angle. The “transverse” momentum of a particle is given by PT = P cos(qcm). • Use h and f to determine the direction of an outgoing particle, where h is the “pseudo-rapidity” defined by h = -log(tan(qcm/2)). • The “rapidity” is defined by y = log((E+pz)/(E-pz))/2 and is equal to h in the limit E >> mc2. Rick Field – Florida/CDF/CMS

15. Quark & Gluon Jets • The CDF calorimeter measures energy deposited in a cell of size DhDf = 0.11×15o, whch is converted into transverse energy, ET = E cos(qcm). • “Jets” are defined to be clusters of transverse energy with a radius R in h-f space. A “jet” is the representation in the detector of an outgoing parton (quark or gluon). • The sum of the ET of the cells within a “jet” corresponds roughly to the ET of the outgoing parton and the position of the cluster in the grid gives the parton’s direction. Can also construct jets from the charged particles! Calorimeter Jets Rick Field – Florida/CDF/CMS

16. “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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. Inclusive Jet Cross Section (DØ ) • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5) • L= 378 pb-1 • Two rapidity bins • Highest PT jet is 630 GeV/c • Compared with NLO QCD (JetRad, No Rsep) today 0.9 fb-1 IMFP2006 Log-Log Scale! Rick Field – Florida/CDF/CMS

26. CDF versus DØ Without threshold corrections! Inclusive Jet (CDF) Inclusive Jet (DØ) • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • CTEQ6.1M m = PT/2 • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5) • CTEQ6.1M m = PT • Threshold corrections (2 loops) Rick Field – Florida/CDF/CMS

27. 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

28. 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

29. 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

30. “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

31. Event Topologies CDF-QCD Data for Theory The goal is to produce data (corrected to the particle level) that can be used by the theorists to tune and improve the QCD Monte-Carlo models that are used to simulate hadron-hadron collisions. Rick Field & Craig Group “Leading Jet” • “Leading Jet” events correspond to the leading calorimeter jet (MidPoint R = 0.7) in the region |h| < 2 with no other conditions. subset • “Back-to-Back Inclusive 2-Jet” events are selected to have at least two jets with Jet#1 and Jet#2 nearly “back-to-back” (Df12 > 150o) with almost equal transverse energies (PT(jet#2)/PT(jet#1) > 0.8) with no other conditions . “Back-to-Back Inc2J” • “Back-to-Back Exclusive 2-Jet” events are selected to have at least two jets with Jet#1 and Jet#2 nearly “back-to-back” (Df12 > 150o) with almost equal transverse energies (PT(jet#2)/PT(jet#1) > 0.8) and PT(jet#3) < 15 GeV/c. subset “Back-to-Back Exc2J” “Charged Jet” • “Leading ChgJet” events correspond to the leading charged particle jet (R = 0.7) in the region |h| < 1 with no other conditions. Rick Field – Florida/CDF/CMS

32. 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

33. “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

34. The “Toward” Region • 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” region. 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” • Data at 1.96 TeV on the charged 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” region. 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). • Data at 1.96 TeV on the scalar ET sum density, dET/dhdf, with |h| < 1 for “leading jet” events as a function of the leading jet pT for the “toward” region. 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). Rick Field – Florida/CDF/CMS

35. The “Away” Region • 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 “away” region. 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” • Data at 1.96 TeV on the charged 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 “away” region. 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). • Data at 1.96 TeV on the scalar ET sum density, dET/dhdf, with |h| < 1 for “leading jet” events as a function of the leading jet pT for the “away” region. 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). Rick Field – Florida/CDF/CMS

36. The “Transverse” Region • 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 “transverse” region. 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” • Data at 1.96 TeV on the charged 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 “transverse” region. 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). • Data at 1.96 TeV on the scalar ET sum density, dET/dhdf, with |h| < 1 for “leading jet” events as a function of the leading jet pT for the “transverse” region. 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). • Data at 1.96 TeV on the charged particle average pT, with pT > 0.5 GeV/c and |h| < 1 for “leading jet” events as a function of the leading jet pT for the “transverse” region. 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). • Data at 1.96 TeV on the charged particle maximum pT, with pT > 0.5 GeV/c and |h| < 1 for “leading jet” events as a function of the leading jet pT for the “transverse” region. 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). Rick Field – Florida/CDF/CMS

37. The “Transverse” Region • 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 “transverse” region. 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” 0.1 density corresponds to 0.42 charged particles in the “transverse” region! • Shows the Data - Theory for 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 “transverse” region for PYTHIA Tune A and HERWIG (without MPI). Rick Field – Florida/CDF/CMS

38. The “Transverse” Region • Data at 1.96 TeV on the charged 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 “transverse” region. 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” 0.1 density corresponds to 420 MeV/c in the “transverse” region! • Shows the Data - Theory for the charged 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 “transverse” region for PYTHIA Tune A and HERWIG (without MPI). Rick Field – Florida/CDF/CMS

39. The “Transverse” Region • Data at 1.96 TeV on the scalar ET sum density, dET/dhdf, with |h| < 1 for “leading jet” events as a function of the leading jet pT for the “transverse” region. 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” 0.4 density corresponds to 1.67 GeV in the “transverse” region! • Shows the Data - Theory for the scalar ET sum density, dET/dhdf, with |h| < 1 for “leading jet” events as a function of the leading jet pT for the “transverse” region for PYTHIA Tune A and HERWIG (without MPI). Rick Field – Florida/CDF/CMS

40. 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

41. The “Transverse” Region • Shows the generator level predictions for the charged fraction, PTsum/ETsum, for PTsum (all pT, |h| < 1) and ETsum (all pT, |h| < 1) and for PTsum (pT > 0.5 GeV/c, |h| < 1) and ETsum (all pT, |h| < 1) for “leading jet” events as a function of the leading jet pT for the “transverse” region from PYTHIA Tune A and HERWIG (without MPI). “Leading Jet” PT(min) = 0 → 0.5 GeV/c • Data at 1.96 TeV on the charged fraction, PTsum/ETsum, for PTsum (pT > 0.5 GeV/c, |h| < 1) and ETsum (all pT, |h| < 1) for “leading jet” events as a function of the leading jet pT for the “transverse” region. 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). Rick Field – Florida/CDF/CMS

42. 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

43. 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

44. 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

45. “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

46. 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

47. 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

48. 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

49. Physics at the Tevatron XXXVI International Meeting on Fundamental Physics From IMFP2006 → IMFP2008 Rick Field University of Florida (for the CDF & D0 Collaborations) 2nd Lecture (Tomorrow) Bosons, Top, and Higgs Palacio de Jabalquinto, Baeza, Spain CDF Run 2 Rick Field – Florida/CDF/CMS