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CDF Collaboration Meeting

From Feynman-Field to the Tevatron. CDF Collaboration Meeting. Toward an Understanding of Hadron-Hadron Collisions. Rick Field University of Florida. La Biodola, Elba Island, Tuscany, Italy. CDF Run 2. From Feynman-Field to the Tevatron.

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CDF Collaboration Meeting

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  1. From Feynman-Field to the Tevatron CDF Collaboration Meeting Toward an Understanding of Hadron-Hadron Collisions Rick Field University of Florida La Biodola, Elba Island, Tuscany, Italy CDF Run 2 Rick Field – Florida/CDF

  2. From Feynman-Field to the Tevatron Toward and Understanding of Hadron-Hadron Collisions 1st hat! Feynman and Field • From 7 GeV/c p0’s to 600 GeV/c Jets. • The “Underlying Event” at the Tevatron (things we don’t understand). • New Run 2 Monte-Carlo Tunes (extrapolations to the LHC). • Let’s find the Higgs! Rick Field – Florida/CDF

  3. The Feynman-Field Days 1973-1983 “Feynman-Field Jet Model” • FF1: “Quark Elastic Scattering as a Source of High Transverse Momentum Mesons”, R. D. Field and R. P. Feynman, Phys. Rev. D15, 2590-2616 (1977). • FFF1: “Correlations Among Particles and Jets Produced with Large Transverse Momenta”, R. P. Feynman, R. D. Field and G. C. Fox, Nucl. Phys. B128, 1-65 (1977). • FF2: “A Parameterization of the properties of Quark Jets”, R. D. Field and R. P. Feynman, Nucl. Phys. B136, 1-76 (1978). • F1: “Can Existing High Transverse Momentum Hadron Experiments be Interpreted by Contemporary Quantum Chromodynamics Ideas?”, R. D. Field, Phys. Rev. Letters 40, 997-1000 (1978). • FFF2: “A Quantum Chromodynamic Approach for the Large Transverse Momentum Production of Particles and Jets”, R. P. Feynman, R. D. Field and G. C. Fox, Phys. Rev. D18, 3320-3343 (1978). • FW1: “A QCD Model for e+e- Annihilation”, R. D. Field and S. Wolfram, Nucl. Phys. B213, 65-84 (1983). My 1st graduate student! Rick Field – Florida/CDF

  4. Rick Field 1968 Before Feynman-Field Rick Field – Florida/CDF

  5. Before Feynman-Field Rick & Jimmie 1970 Rick & Jimmie 1968 Rick & Jimmie 1972 (pregnant!) Rick & Jimmie at CALTECH 1973 Rick Field – Florida/CDF

  6. Erice 1982 The Feynman-Field Days Rick Field Chris Quigg Giorgio Bellettini Keith Ellis Keith Ellis Rick Field – Florida/CDF

  7. Hadron-Hadron Collisions FF1 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

  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

  9. Quark-Quark Black-Box Model Predict particle ratios FF1 1977 (preQCD) Predict increase with increasing CM energy W “Beam-Beam Remnants” Predict overall event topology (FFF1 paper 1977) 7 GeV/c p0’s! Rick Field – Florida/CDF

  10. Telagram from Feynman July 1976 SAW CRONIN AM NOW CONVINCED WERE RIGHT TRACK QUICK WRITE FEYNMAN Rick Field – Florida/CDF

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

  12. 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

  13. 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

  14. (bk) (ka) (cb) (ba) cc pair bb pair A Parameterization of the Properties of Jets Field-Feynman 1978 • Assumed that jets could be analyzed on a “recursive” principle. Secondary Mesons (after decay) • Let f(h)dh be the probability that the rank 1 meson leaves fractional momentum h to the remaining cascade, leaving quark “b” with momentum P1 = h1P0. Rank 2 Rank 1 • Assume that the mesons originating from quark “b” are distributed in presisely the same way as the mesons which came from quark a (i.e. same function f(h)), leaving quark “c” with momentum P2 = h2P1 = h2h1P0. Primary Mesons continue • Add in flavor dependence by letting bu = probabliity of producing u-ubar pair, bd = probability of producing d-dbar pair, etc. Calculate F(z) from f(h) and bi! • Let F(z)dz be the probability of finding a meson (independent of rank) with fractional mementum z of the original quark “a” within the jet. Original quark with flavor “a” and momentum P0 Rick Field – Florida/CDF

  15. Feynman-Field Jet Model R. P. Feynman ISMD, Kaysersberg, France, June 12, 1977 Feynman quote from FF2 “The predictions of the model are reasonable enough physically that we expect it may be close enough to reality to be useful in designing future experiments and to serve as a reasonable approximation to compare to data. We do not think of the model as a sound physical theory, ....” Rick Field – Florida/CDF

  16. Monte-Carlo Simulationof Hadron-Hadron Collisions FF1-FFF1 (1977) “Black-Box” Model FF2 (1978) Monte-Carlo simulation of “jets” F1-FFF2 (1978) QCD Approach FFFW “FieldJet” (1980) QCD “leading-log order” simulation of hadron-hadron collisions “FF” or “FW” Fragmentation the past today ISAJET (“FF” Fragmentation) HERWIG (“FW” Fragmentation) PYTHIA tomorrow SHERPA PYTHIA 6.3 Rick Field – Florida/CDF

  17. hadrons Field-Feynman CDF Distribution of Particles in Jets Monte-Carlo Simulationof Quark and Gluon Jets • ISAJET: Evolve the parton-shower from Q2 (virtual photon invariant mass) to Qmin ~ 5 GeV. Use a complicated fragmentation model to evolve from Qmin to outgoing hadrons. • HERWIG: Evolve the parton-shower from Q2 (virtual photon invariant mass) to Qmin ~ 1 GeV. Form color singlet clusters which “decay” into hadrons according to 2-particle phase space. • MLLA: Evolve the parton-shower from Q2 (virtual photon invariant mass) to Qmin ~ 230 MeV. Assume that the charged particles behave the same as the partons with Nchg/Nparton = 0.56! Q2 MLLA Curve! 200 MeV 5 GeV 1 GeV Rick Field – Florida/CDF

  18. “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

  19. Jet Algorithms • Clustering algorithms are used to combine calorimeter towers or charged particles into “jets” in order to study the event topology and to compare with the QCD Monte-Carlo Models. • We do not detect partons! The outgoing partons fragment into hadrons before they travel a distance of about the size of the proton. At long distances the partons manifest themselves as “jets”. The “underlying event” can also form “jets”. Most “jets” are a mixture of particles arising from the “hard” outgoing partons and the “underlying event”. • Since we measure hadrons every observable is infrared and collinear safe. There are no divergences at the hadron level! • Every “jet” algorithms correspond to a different observable and different algorithms give different results. • Studying the difference between the algorithms teaches us about the event structure. Rick Field – Florida/CDF

  20. Jet Corrections & Extrapolations • Calorimeter Level Jets → Hadron Level Jets: • We measure “jets” at the “hadron level” in the calorimeter. • We certainly want to correct the “jets” for the detector resolution and efficiency. • Also, we must correct the “jets” for “pile-up”. • Must correct what we measure back to the true “hadron level” (i.e. particle level) observable! Hadron ← Parton I do not believe we should extrapolate the data to the parton level! We should publish what we measure (i.e. hadron level with the “underlying event”)! To compare with theory we should “extrapolate” the parton level to the hadron level (i.e. add hadronization and the “underlying event” to the parton level)! PYTHIA, HERWIG, MC@NLO • Particle Level Jets (with the “underlying event” removed): • Do we want to make further model dependent corrections? • Do we want to try and subtract the “underlying event” from the observed “particle level” jets. • This cannot really be done, but if you trust the Monte-Carlo modeling of the “underlying event” you can do it by using the Monte-Carlo models (use PYTHIA Tune A). • This is no longer an observable, it is a model dependent extrapolation! Useless without a model of hadronization! • Hadron Level Jets → Parton Level Jets: • Do we want to use the data to try and extrapolate back to the parton level? What parton level, PYTHIA (Leading Log) or fixed order NLO? • 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 (use PYTHIA Tune A) including ISR and FSR. • Cannot extrapolate the data to fixed order NLO! Next-to-leading order parton level calculation 0, 1, 2, or 3 partons! Rick Field – Florida/CDF

  21. Infrared Safety (Parton Level) Soft parton emission changes jet multiplicity Collinear Safety (Parton Level) above threshold (1 jet) below threshold (no jets) Good and Bad Algorithms • In order to correct what we see in the calorimeter back to the hadron level we must use an algorithm that can be defined at both the calorimeter and particle level. • If you insist on extrapolating the data to the parton level then it is better to use an algorithm that is well defined at the parton level (i.e. infrared and collinear safe at the parton level). • If you hadronize the parton level and add the “underlying event” (i.e. PYTHIA, HERWIG, MC@NLO) then you do not care if the algorithm is infrared and collinear safe at the parton level. You can predict any hadron level observable! Rick Field – Florida/CDF

  22. Four Jet Algorithms Towers not included in a jet (i.e. “dark towers”)! Bad • JetClu is bad because the algorithm cannot be defined at the particle level. • The MidPoint and Modified MidPoint (i.e. Search Cone) algorithms are not infrared and collinear safe at the parton level. Rick Field – Florida/CDF

  23. 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

  24. KT Inclusive Jet Cross Section • KT Algorithm (D = 0.7) • Data corrected to the hadron level • L= 385 pb-1 • 0.1 < |yjet| < 0.7 • Compared with NLO QCD (JetRad) corrected to the hadron level. Sensitive to UE + hadronization effects for PT < 300 GeV/c! Rick Field – Florida/CDF

  25. Search Cone Inclusive Jet Cross Section • Modified MidPoint Cone Algorithm (R = 0.7, fmerge = 0.75) • Data corrected to the hadron level and the parton level • L= 1.04 fb-1 • 0.1 < |yjet| < 0.7 • Compared with NLO QCD (JetRad, Rsep = 1.3) Sensitive to UE + hadronization effects for PT < 200 GeV/c! Rick Field – Florida/CDF

  26. MidPoint Cone Algorithm (R = 0.7) Hadronization and “Underlying Event” Corrections Note that DØ does not make any corrections for hadronization or the “underlying event”!? • Compare the hadronization and “underlying event” corrections for the KT algorithm (D = 0.7) and the MidPoint algorithm (R = 0.7)! • We see that the KT algorithm (D = 0.7) is slightly more sensitive to the underlying event than the cone algorithm (R = 0.7), but with a good model of the “underlying event” both cross sections can be measured at the Tevatrun! The KT algorithm is slightly more sensitive to the “underlying event”! Rick Field – Florida/CDF

  27. KT Inclusive Jet Cross Section • 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 (JetRad) with CTEQ6.1 Excellent agreement over all rapidity ranges! Rick Field – Florida/CDF

  28. The “Transverse” Regionsas defined by the Leading Jet Charged Particle Df Correlations pT > 0.5 GeV/c |h| < 1 Look at the charged particle density in the “transverse” region! • Look at charged particle correlations in the azimuthal angle Df relative to the leading calorimeter jet (JetClu R = 0.7, |h| < 2). • Define |Df| < 60o as “Toward”, 60o < -Df < 120o and 60o < Df < 120o as “Transverse 1” and “Transverse 2”, and |Df| > 120o as “Away”. Each of the two “transverse” regions have area DhDf = 2x60o = 4p/6. The overall “transverse” region is the sum of the two transverse regions (DhDf = 2x120o = 4p/3). “Transverse” region is very sensitive to the “underlying event”! Rick Field – Florida/CDF

  29. Run 1 PYTHIA Tune A CDF Default! PYTHIA 6.206 CTEQ5L • Plot shows the “transverse” charged particle density versus PT(chgjet#1) compared to the QCD hard scattering predictions of two tuned versions of PYTHIA 6.206 (CTEQ5L, Set B (PARP(67)=1)andSet A(PARP(67)=4)). Run 1 Analysis Old PYTHIA default (more initial-state radiation) Old PYTHIA default (more initial-state radiation) New PYTHIA default (less initial-state radiation) New PYTHIA default (less initial-state radiation) Rick Field – Florida/CDF

  30. Charged Particle Density Df Dependence Refer to this as a “Leading Jet” event • Look at the “transverse” region as defined by the leading jet (JetClu R = 0.7, |h| < 2) or by the leading two jets (JetClu R = 0.7, |h| < 2). “Back-to-Back” 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 (ET(jet#2)/ET(jet#1) > 0.8) and with ET(jet#3) < 15 GeV. Subset Refer to this as a “Back-to-Back” event • Shows the Df dependence of the charged particle density, dNchg/dhdf, for charged particles in the range pT > 0.5 GeV/c and |h| < 1 relative to jet#1 (rotated to 270o) for 30 < ET(jet#1) < 70 GeV for “Leading Jet” and “Back-to-Back” events. Rick Field – Florida/CDF

  31. Hard Radiation! “Transverse” PTsum Density vs ET(jet#1) “Leading Jet” “Back-to-Back” Min-Bias 0.24 GeV/c per unit h-f • Shows the average charged PTsum density, dPTsum/dhdf, in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus ET(jet#1) for “Leading Jet” and “Back-to-Back” events. • Compares the (uncorrected) data with PYTHIA Tune A and HERWIG (without MPI) after CDFSIM. Rick Field – Florida/CDF

  32. “TransMAX/MIN” PTsum Density PYTHIA Tune A vs HERWIG PYTHIA Tune A does a fairly good job fitting the PTsum density in the “transverse” region! HERWIG does a poor job! “Back-to-Back” “Leading Jet” • Shows the charged particle PTsum density, dPTsum/dhdf, in the “transMAX” and “transMIN” region (pT > 0.5 GeV/c, |h| < 1) versus PT(jet#1) for “Leading Jet” and “Back-to-Back” events. • Compares the (corrected) data with PYTHIA Tune A (with MPI) and HERWIG (without MPI) at the particle level. Rick Field – Florida/CDF

  33. “TransMAX/MIN” ETsum Density PYTHIA Tune A vs HERWIG “Back-to-Back” “Leading Jet” Neither PY Tune A or HERWIG fits the ETsum density in the “transferse” region! HERWIG does slightly better than Tune A! • Shows the data on the tower ETsum density, dETsum/dhdf, in the “transMAX” and “transMIN” region (ET > 100 MeV, |h| < 1) versus PT(jet#1) for “Leading Jet” and “Back-to-Back” events. • Compares the (corrected) data with PYTHIA Tune A (with MPI) and HERWIG (without MPI) at the particle level (all particles, |h| < 1). Rick Field – Florida/CDF

  34. “TransDIF” ETsum Density PYTHIA Tune A vs HERWIG “Leading Jet” “Back-to-Back” “transDIF” is more sensitive to the “hard scattering” component of the “underlying event”! • Use the leading jet to define the MAX and MIN “transverse” regions on an event-by-event basis with MAX (MIN) having the largest (smallest) charged PTsum density. • Shows the “transDIF” = MAX-MIN ETsum density, dETsum/dhdf, for all particles (|h| < 1) versus PT(jet#1) for “Leading Jet” and “Back-to-Back” events. Rick Field – Florida/CDF

  35. Possible Scenario?? • PYTHIA Tune A fits the charged particle PTsum density for pT > 0.5 GeV/c, but it does not produce enough ETsum for towers with ET > 0.1 GeV. • It is possible that there is a sharp rise in the number of particles in the “underlying event” at low pT (i.e. pT < 0.5 GeV/c). • Perhaps there are two components, a vary “soft” beam-beam remnant component (gaussian or exponential) and a “hard” multiple interaction component. Rick Field – Florida/CDF

  36. “Hard Scattering” Component QCD Monte-Carlo Models:Lepton-Pair Production • Start with the perturbative Drell-Yan muon pair production and add initial-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). • 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

  37. The “Central” Regionin Drell-Yan Production Look at the charged particle density and the PTsum density in the “central” region! Charged Particles(pT > 0.5 GeV/c, |h| < 1) • Look at the “central” region after removing the lepton-pair. • Study the charged particles (pT > 0.5 GeV/c, |h| < 1) and form the charged particle density, dNchg/dhdf, and the charged scalar pT sum density, dPTsum/dhdf, by dividing by the area in h-f space. After removing the lepton-pair everything else is the “underlying event”! Rick Field – Florida/CDF

  38. CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L UE Parameters • Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), Tune A25 (<pT(Z)> = 10.1 GeV/c), and Tune A50 (<pT(Z)> = 11.2 GeV/c). ISR Parameter Vary the intrensic KT! Intrensic KT Rick Field – Florida/CDF

  39. CDF Run 1 PT(Z) Tune used by the CDF-EWK group! PYTHIA 6.2 CTEQ5L • Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), and PYTHIA Tune AW (<pT(Z)> = 11.7 GeV/c). UE Parameters ISR Parameters Effective Q cut-off, below which space-like showers are not evolved. Intrensic KT The Q2 = kT2 in as for space-like showers is scaled by PARP(64)! Rick Field – Florida/CDF

  40. Df Jet#1-Jet#2 Jet#1-Jet#2 Df Distribution Jet-Jet Correlations (DØ) • MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5) • L= 150 pb-1 (Phys. Rev. Lett. 94 221801 (2005)) • Data/NLO agreement good. Data/HERWIG agreement good. • Data/PYTHIA agreement good provided PARP(67) = 1.0→4.0 (i.e. like Tune A, best fit 2.5). Rick Field – Florida/CDF

  41. CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L • Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune DW, and HERWIG. UE Parameters ISR Parameters Tune DW uses D0’s perfered value of PARP(67)! Intrensic KT Tune DW has a lower value of PARP(67) and slightly more MPI! Rick Field – Florida/CDF

  42. “Transverse” Nchg Density PYTHIA 6.2 CTEQ5L Three different amounts of MPI! UE Parameters • Shows the “transverse” charged particle density, dN/dhdf, versus PT(jet#1) for “leading jet” events at 1.96 TeV for PYTHIA Tune A, Tune AW, Tune DW, Tune BW, and HERWIG (without MPI). ISR Parameter • Shows the “transverse” charged particle density, dN/dhdf, versus PT(jet#1) for “leading jet” events at 1.96 TeV for Tune DW, ATLAS, and HERWIG (without MPI). Three different amounts of ISR! Intrensic KT Rick Field – Florida/CDF

  43. “Transverse” PTsum Density PYTHIA 6.2 CTEQ5L Three different amounts of MPI! UE Parameters • Shows the “transverse” charged PTsum density, dPT/dhdf, versus PT(jet#1) for “leading jet” events at 1.96 TeV for PYTHIA Tune A, Tune AW, Tune DW, Tune BW, and HERWIG (without MPI). ISR Parameter • Shows the “transverse” charged PTsum density, dPT/dhdf, versus PT(jet#1) for “leading jet” events at 1.96 TeV for Tune DW, ATLAS, and HERWIG (without MPI). Three different amounts of ISR! Intrensic KT Rick Field – Florida/CDF

  44. Bruce Knuteson Khaldoun Makhoul Georgios Choudalakis Markus Klute Conor Henderson Ray Culbertson Gene Flanagan MIT Search Scheme 12 Exclusive 3 Jet Final State Challenge CDF Data At least 1 Jet (“trigger” jet) (PT > 40 GeV/c, |h| < 1.0) Normalized to 1 PYTHIA Tune A Exactly 3 jets (PT > 20 GeV/c, |h| < 2.5) R(j2,j3) Order Jets by PT Jet1 highest PT, etc. Rick Field – Florida/CDF

  45. R > 1.0 3Jexc R(j2,j3) Normalized The data have more 3 jet events with small R(j2,j3)!? • Let Ntrig40 equal the number of events with at least one jet with PT > 40 geV and |h| < 1.0 (this is the “offline” trigger). • Let N3Jexc20 equal the number of events with exactly three jets with PT > 20 GeV/c and |h| < 2.5 which also have at least one jet with PT > 40 GeV/c and |h| < 1.0. Normalized to N3JexcFr • Let N3JexcFr = N3Jexc20/Ntrig40. The is the fraction of the “offline” trigger events that are exclusive 3-jet events. • The CDF data on dN/dR(j2,j3) at 1.96 TeV compared with PYTHIA Tune AW (PARP(67)=4), Tune DW (PARP(67)=2.5), Tune BW (PARP(67)=1). • PARP(67) affects the initial-state radiation which contributes primarily to the region R(j2,j3) > 1.0. Rick Field – Florida/CDF

  46. R < 1.0 3Jexc R(j2,j3) Normalized I do not understand the excess number of events with R(j2,j3) < 1.0. Perhaps this is related to the “soft energy” problem?? For now the best tune is PYTHIA Tune DW. • Let Ntrig40 equal the number of events with at least one jet with PT > 40 geV and |h| < 1.0 (this is the “offline” trigger). • Let N3Jexc20 equal the number of events with exactly three jets with PT > 20 GeV/c and |h| < 2.5 which also have at least one jet with PT > 40 GeV/c and |h| < 1.0. Normalized to N3JexcFr • Let N3JexcFr = N3Jexc20/Ntrig40. The is the fraction of the “offline” trigger events that are exclusive 3-jet events. • The CDF data on dN/dR(j2,j3) at 1.96 TeV compared with PYTHIA Tune DW (PARP(67)=2.5) and HERWIG (without MPI). • Final-State radiation contributes to the region R(j2,j3) < 1.0. • If you ignore the normalization and normalize all the distributions to one then the data prefer Tune BW, but I believe this is misleading. Rick Field – Florida/CDF

  47. Drell-Yan Production (Run 2 vs LHC) Lepton-Pair Transverse Momentum • Average Lepton-Pair transverse momentum at the Tevatron and the LHC for PYTHIA Tune DW and HERWIG (without MPI). <pT(m+m-)> is much larger at the LHC! Shapes of the pT(m+m-) distribution at the Z-boson mass. Z • Shape of the Lepton-Pair pT distribution at the Z-boson mass at the Tevatron and the LHC for PYTHIA Tune DW and HERWIG (without MPI). Rick Field – Florida/CDF

  48. The “Underlying Event” inDrell-Yan Production The “Underlying Event” Charged particle density versus M(pair) • Charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune AW and HERWIG (without MPI). HERWIG (without MPI) is much less active than PY Tune AW (with MPI)! “Underlying event” much more active at the LHC! Z Z • Charged particle density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune AW and HERWIG (without MPI). Rick Field – Florida/CDF

  49. Extrapolations to the LHC:Drell-Yan Production Charged particle density versus M(pair) The “Underlying Event” • Average charged particle density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune A, Tune AW, Tune BW, Tune DW and HERWIG (without MPI). Tune DW and DWT are identical at 1.96 TeV, but have different MPI energy dependence! Z Z • Average charged particle density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune DW, Tune DWT, ATLAS and HERWIG (without MPI). Rick Field – Florida/CDF

  50. Extrapolations to the LHC:Drell-Yan Production Charged particle charged PTsum density versus M(pair) The “Underlying Event” • Average charged PTsum density versus the lepton-pair invariant mass at 1.96 TeV for PYTHIA Tune A, Tune AW, Tune BW, Tune DW and HERWIG (without MPI). The ATLAS tune has a much “softer” distribution of charged particles than the CDF Run 2 Tunes! Z Z • Average charged PTsum density versus the lepton-pair invariant mass at 14 TeV for PYTHIA Tune DW, Tune DWT, ATLAS and HERWIG (without MPI). Rick Field – Florida/CDF

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