Collisions Rick s View of Hadron Collisions

st Workshop on Energy Scaling in Hadron-Hadron Collisions Rick s View of Hadron Collisions Rick Field University of Florida Fermilab 2009 Outline of Talk The early days of Feynman-Field Phenomenology. Proton Underlying Event Outgoing Parton PT(hard) Initial-State Radiation AntiProton Underlying Event Studying min-bias collisions and the underlying event in Run at CDF. Outgoing Parton Final-State Radiation Tuning the QCD Monte-Carlo model generators. Studying the associated charged particle densities in min-bias collisions. CDF Run 2 CMS at the LHC Rick Field Florida/CDF/CMS Page

Toward and Understanding of Hadron-Hadron Collisions Feynman-Field Phenomenology st hat! Feynman and Field From 7 GeV/c π 0 s to 600 GeV/c Jets. The early days of trying to understand and simulate hadronhadron collisions. Proton Underlying Event Outgoing Parton PT(hard) Initial-State Radiation AntiProton Underlying Event Outgoing Parton Final-State Radiation Rick Field Florida/CDF/CMS Page 2

Hadron-Hadron Collisions FF 977 What happens when two hadrons collide at high energy? 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. Hadron??? Hadron Parton-Parton Scattering Outgoing Parton Soft Collision (no large transverse momentum) Occasionally there will be a large transverse momentum meson. Question: Where did it come from? Hadron Hadron We assumed it came from quark-quark elastic scattering, but we did not know how to calculate it! Black-Box Model Outgoing Parton high P T meson Rick Field Florida/CDF/CMS Page 3

Hadron-Hadron Collisions FF 977 What happens when two hadrons collide at high energy? Hadron Feynman quote from FF??? The model we shall choose is not a popular one, Most of the time the hadrons ooze so that we will not duplicate too much of the through each other and work fall apart of others (i.e. who are similarly analyzing no hard scattering). The various outgoing models (e.g. constituent interchange particles continue in roughly model, multiperipheral the same models, etc.). We shall Parton-Parton Scattering direction as initial proton assume and that the high P Outgoing Parton T particles arise from antiproton. direct hard collisions between constituent quarks in the incoming particles, which Occasionally there will fragment be a large or cascade down Hadron into several hadrons. transverse momentum meson. Question: Where did it come from? Hadron Soft Collision (no large transverse momentum) Hadron We assumed it came from quark-quark elastic scattering, but we did not know how to calculate it! Black-Box Model Outgoing Parton high P T meson Rick Field Florida/CDF/CMS Page 4

Quark Distribution Functions determined from deep-inelastic lepton-hadron collisions Quark-Quark Black-Box Box Model FF 977 No gluons! Quark-Quark Cross-Section Unknown! Deteremined from hadron-hadron collisions. Quark Fragmentation Functions determined from e + e - annihilations Rick Field Florida/CDF/CMS Page 5

Quark Distribution Functions determined from deep-inelastic lepton-hadron collisions Quark-Quark Black-Box Box Model FF 977 Feynman quote from FF 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. No gluons! Quark-Quark Cross-Section Unknown! Deteremined from hadron-hadron collisions. Quark Fragmentation Functions determined from e + e - annihilations Rick Field Florida/CDF/CMS Page 6

Quark-Quark Black-Box Box Model Predict particle ratios FF 977 Predict increase with increasing CM energy W Beam-Beam Remnants Predict overall event topology (FFF paper 977) 7 GeV/c π 0 s! Rick Field Florida/CDF/CMS Page 7

Feynman Talk at Coral Gables (December 976) st transparency Last transparency Feynman-Field Jet Model Rick Field Florida/CDF/CMS Page 8

QCD Approach: Quarks & Gluons Quark & Gluon Fragmentation Functions Q 2 dependence predicted from QCD FFF2 978 Parton Distribution Functions Q 2 dependence predicted from QCD Quark & Gluon Cross-Sections Calculated from QCD Rick Field Florida/CDF/CMS Page 9

QCD Approach: Quarks & Gluons Quark & Gluon Fragmentation Functions Q 2 dependence predicted from QCD FFF2 978 Parton Distribution Functions Q 2 dependence predicted from QCD 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. Quark & Gluon Cross-Sections Calculated from QCD Rick Field Florida/CDF/CMS Page 0

continue Secondary Mesons (after decay) Rank 2 cc pair (cb) (bk) bb pair (ba) (ka) Rank Original quark with flavor a and momentum P 0 A Parameterization of the Properties of Jets Field-Feynman 978 Assumed that jets could be analyzed on a recursive principle. Let f(η)dη be the probability that the rank meson leaves fractional momentum η to the remaining cascade, leaving quark b with momentum P = η P 0. Assume that the mesons originating from quark b are distributed in presisely the same way as the mesons which Primary Mesons came from quark a (i.e. same function f(η)), leaving quark c with momentum P 2 = η 2 P = η 2 η P 0. Calculate F(z) from f(η) and β i! Add in flavor dependence by letting β u = probabliity of producing u-ubar pair, β d = probability of producing d- dbar pair, etc. 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. Rick Field Florida/CDF/CMS Page

Feynman-Field Field Jet Model R. P. Feynman ISMD, Kaysersberg, France, June 2, 977 Rick Field Florida/CDF/CMS Page 2

Feynman-Field Field Jet Model R. P. Feynman ISMD, Kaysersberg, France, June 2, 977 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/CMS Page 3

High P T Jets Feynman, Field, & Fox (978) CDF (2006) Predict large jet cross-section 30 GeV/c! 600 GeV/c Jets! 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 P T discussed here. Rick Field Florida/CDF/CMS Page 4

CDF DiJet Event: M(jj).4 TeV E T jet = 666 GeV E T jet2 = 633 GeV E sum =,299 GeV M(jj) =,364 GeV M(jj)/E cm 70%!! Rick Field Florida/CDF/CMS Page 5

Monte-Carlo Simulation of Hadron-Hadron Collisions F-FFF2 (978) QCD Approach FF-FFF (977) Black-Box Model FF2 (978) Monte-Carlo simulation of jets my early days FFFW FieldJet (980) QCD leading-log order simulation of hadron-hadron collisions FF or FW Fragmentation yesterday ISAJET ( FF Fragmentation) HERWIG ( FW Fragmentation) PYTHIA ( String Fragmentation) today SHERPA PYTHIA 6.4 HERWIG++ Rick Field Florida/CDF/CMS Page 6

The Fermilab Tevatron CDF SciCo Shift December 2-9, 2008 Proton mile CDF AntiProton Proton 2 TeV AntiProton I joined CDF in January 998. Acquired 4728 nb - during 8 hour owl shift! Rick Field Florida/CDF/CMS Page 7

The Fermilab Tevatron CDF SciCo Shift December 2-9, 2008 My wife Jimmie on shift with me! Proton CDF mile AntiProton Proton 2 TeV I joined CDF in January 998. AntiProton Acquired 4728 nb- during 8 hour owl shift! Rick Field Florida/CDF/CMS Page 8

Elastic Scattering Proton-AntiProton Collisions at the Tevatron Single Diffraction M The CDF Min-Bias trigger picks up most of the hard core cross-section plus a Double small Diffraction amount of single & double diffraction. M M 2 Proton σ tot = σ EL + σ SD +σ DD +σ HC.8 TeV: 78mb = 8mb + 9mb + (4-7)mb + (47-44)mb The hard core component contains both hard and soft collisions. Inelastic Non-Diffractive Component Soft Hard Core (no hard scattering) Hard Core AntiProton Beam-Beam Counters 3.2 < η < 5.9 Hard Hard Core (hard scattering) Proton Underlying Event CDF Min-Bias trigger charged particle in forward BBC AND charged particle in backward BBC Outgoing Parton Final-State Radiation Outgoing Parton PT(hard) AntiProton Underlying Event Initial-State Radiation Rick Field Florida/CDF/CMS Page 9

QCD Monte-Carlo Models: High Transverse Momentum Jets Hard Scattering Outgoing Parton Initial-State Radiation PT(hard) Hard Scattering Jet Jet Initial-State Radiation Outgoing Parton PT(hard) Hard Scattering Component Proton Underlying Event AntiProton Underlying Event Outgoing Parton Final-State Radiation Outgoing Parton Jet Final-State Radiation Proton Underlying Event AntiProton Underlying Event Underlying Event Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and finalstate gluon radiation (in the leading log approximation or modified leading log approximation). 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 Of course the outgoing colored partons fragment into hadron jet and inevitably underlying event background to most collider observables observables receive contributions from initial and final-state radiation. and having good understand of it leads to more precise collider measurements! Rick Field Florida/CDF/CMS Page 20

Particle Densities 2π η φ = 4π = 2.6 Charged Particles p T > 0.5 GeV/c η < CDF Run 2 Min-Bias CDF Run 2 Min-Bias Observable Average Average Density per unit η-φ φ 3 charged particles Nchg PTsum (GeV/c) Number of Charged Particles (p T > 0.5 GeV/c, η < ) Scalar p T sum of Charged Particles (p T > 0.5 GeV/c, η < ) 3.7 +/- 0.3 2.97 +/- 0.23 0.252 +/- 0.025 0.236 +/- 0.08 3 GeV/c PTsum dnchg/dηdφ = /4π 3/4π = 0.08 0.24 Divide by 4π 0 - η + dptsum/dηdφ = /4π 3/4π GeV/c = 0.08 0.24 GeV/c Study the charged particles (p T > 0.5 GeV/c, η < ) and form the charged particle density, dnchg/dηdφ, and the charged scalar p T sum density, dptsum/dηdφ. Rick Field Florida/CDF/CMS Page 2

CDF Run : Evolution of Charged Jets Underlying Event region very sensitive to the underlying event! Charged Jet # Direction Toward Toward-Side Jet φ Charged Particle φ Correlations P T > 0.5 GeV/c η < CDF Run Analysis Charged Jet # Direction φ 2π Away Region Transverse Region Look at the charged particle density in the transverse region! Away Toward φ Leading Jet Toward Region Transverse Region Away-Side Jet Away 0 Away Region - η + Look at charged particle correlations in the azimuthal angle φ relative to the leading charged particle jet. Define φ φ < 60 o as Toward, 60 o < φ φ < 20 o as, and φ φ > 20 o as Away. All three regions have the same size in η-φ space, ηx φ φ = 2x20 o = 4π/3. Rick Field Florida/CDF/CMS Page 22

Run Charged Particle Density p T Distribution "Transverse" Charged Density "Transverse" Charged Particle Density: dn/dηdφ.00 CDF Run 0.75 0.50 0.25 0.00 data uncorrected CDF Min-Bias CDF JET20 Factor of 2!.8 TeV η <.0 PT>0.5 GeV/c 0 5 0 5 20 25 30 35 40 45 50 PT(charged jet#) (GeV/c) Charged Particle Jet # Direction φ Toward Away Min-Bias Compares the average transverse charge particle density with the average Min-Bias charge particle density ( η <, p T >0.5 GeV). Shows how the transverse charge particle density and the Min-Bias charge particle density is distributed in p T. Rick Field Florida/CDF/CMS Page 23

Run Charged Particle Density p T Distribution "Transverse" Charged Density Min-Bias.00 0.75 0.50 0.25 0.00 "Transverse" Charged Particle Density: dn/dηdφ CDF Run data uncorrected P T (charged jet#) > 30 GeV/c <dn chg /dηdφ> = 0.56 CDF Run Min-Bias data <dn chg /dηdφ> = 0.25 Factor of 2! 0 5 0 5 20 25 30 35 40 45 50 PT(charged jet#) (GeV/c) CDF Min-Bias CDF JET20.8 TeV η <.0 PT>0.5 GeV/c Charged Density dn/dηdφdpt (/GeV/c).0E+00.0E-0.0E-02.0E-03.0E-04.0E-05.0E-06 Min-Bias Charged Particle Density.8 TeV η < PT>0.5 GeV/c "Transverse" PT(chgjet#) > 5 GeV/c 0 2 4 6 8 0 2 4 PT(charged) (GeV/c) CDF Run data uncorrected "Transverse" PT(chgjet#) > 30 GeV/c Compares the average transverse charge particle density with the average Min-Bias charge particle density ( η <, p T >0.5 GeV). Shows how the transverse charge particle density and the Min-Bias charge particle density is distributed in p T. Rick Field Florida/CDF/CMS Page 24

Multiple Hard Parton Collision Interaction Proton initial-state radiation outgoing parton outgoing parton MPI: Multiple Parton Interactions final-state radiation AntiProton initial-state radiation Hard Component outgoing jet PYTHIA models the soft component of the underlying event with color string fragmentation, but in addition includes a contribution arising from multiple parton interactions (MPI) in which one interaction is hard and the other is semi-hard. color string color string The probability that a hard scattering events also contains a semi-hard multiple parton interaction can be varied but adjusting the cut-off for the MPI. One can also adjust whether the probability of a MPI depends on the P T of the hard scattering, P T (hard) (constant cross section or varying with impact parameter). One can adjust the color connections and flavor of the MPI (singlet or nearest neighbor, q-qbar or glue-glue). Also, one can adjust how the probability of a MPI depends on P T (hard) (single or double Gaussian matter distribution). + final-state radiation Semi-Hard MPI or Beam-Beam Remnants Soft Component Rick Field Florida/CDF/CMS Page 25

Tuning PYTHIA: Multiple Parton Interaction Parameters Parameter Default Description PARP(83) PARP(84) PARP(85) PARP(86) 0.5 0.2 0.33 0.66 Double-Gaussian: Fraction of total hadronic matter within PARP(84) Double-Gaussian: Fraction of the overall hadron radius containing the fraction PARP(83) of the total hadronic matter. Probability that the MPI produces two gluons with color connections to the nearest neighbors. Probability that the MPI produces two gluons either as described by PARP(85) or as a closed gluon Affects loop. the The amount remaining of fraction consists of quark-antiquark initial-state radiation! pairs. Hard Core Color String Multiple Parton Interaction Color String Multiple Parton Determine Interaction by comparing with 630 GeV data! Color String Hard-Scattering Cut-Off PT0 PARP(89) PARP(90) PARP(67) TeV 0.6.0 Determines the reference energy E 0. Determines the energy dependence of the cut-off P T0 as follows P T0 (E cm ) = P T0 (E cm /E 0 ) ε with ε = PARP(90) A scale factor that determines the maximum parton virtuality for space-like showers. The larger the value of PARP(67) the more initialstate radiation. PT0 (GeV/c) 5 4 3 2 PYTHIA 6.206 Take E 0 =.8 TeV ε = 0.25 (Set A)) ε = 0.6 (default) 00,000 0,000 00,000 Reference point at.8 TeV CM Energy W (GeV) Rick Field Florida/CDF/CMS Page 26

PYTHIA default parameters Parameter MSTP(8) MSTP(82) PARP(8) PARP(82) PARP(89) PARP(90) PARP(67) 6.5.4.55 4.0 PYTHIA 6.206 Defaults MPI constant probability 6.25.9 2.,000 0.6 4.0 6.58.9 2.,000 0.6.0 6.206.9.9,000 0.6.0 "Transverse" Charged Density scattering.00 0.75 0.50 0.25 0.00 "Transverse" Charged Particle Density: dn/dηdφ CDF Data data uncorrected theory corrected Pythia 6.206 (default) MSTP(82)= PARP(8) =.9 GeV/c 0 5 0 5 20 25 30 35 40 45 50 PT(charged jet#) (GeV/c).8 TeV η <.0 PT>0.5 GeV CTEQ3L CTEQ4L CTEQ5L CDF Min-Bias CDF JET20 Plot shows the charged particle density versus P T (chgjet#) compared to the QCD hard scattering predictions of PYTHIA 6.206 (P T (hard) > 0) using the default parameters for multiple parton interactions and CTEQ3L, CTEQ4L, and CTEQ5L. Note Change PARP(67) = 4.0 (< 6.38) PARP(67) =.0 (> 6.38) Default parameters give very poor description of the underlying event! Rick Field Florida/CDF/CMS Page 27

PYTHIA 6.206 CTEQ5L Parameter MSTP(8) MSTP(82) PARP(82) PARP(83) PARP(84) PARP(85) PARP(86) PARP(89) PARP(90) PARP(67) Tune B 0.5 0.4.0.8 TeV 0.25.0 New PYTHIA default (less initial-state radiation) 4.9 GeV.0 Run PYTHIA Tune A Tune A 4 2.0 GeV 0.5 0.4 0.9 0.95.8 TeV 0.25 4.0 CDF Default! "Transverse" Charged Particle Density: dn/dηdφ "Transverse" Charged Density.00 0.75 0.50 0.25 0.00 CDF Preliminary data uncorrected theory corrected CTEQ5L Plot shows the transverse charged particle density versus P T (chgjet#) compared to the QCD hard scattering predictions of two tuned versions of PYTHIA 6.206 (CTEQ5L, Set B (PARP(67)=) and Set A (PARP(67)=4)). Old PYTHIA default (more initial-state radiation) PYTHIA 6.206 (Set B) PARP(67)= PYTHIA 6.206 (Set A) PARP(67)=4 0 5 0 5 20 25 30 35 40 45 50 PT(charged jet#) (GeV/c) Run Analysis.8 TeV η <.0 PT>0.5 GeV Rick Field Florida/CDF/CMS Page 28

dn/dηdφ.0 0.8 0.6 0.4 0.2 0.0 CDF Published Charged Particle Density: dn/dηdφ Pythia 6.206 Set A CDF Min-Bias.8 TeV -4-3 -2-0 2 3 4 Pseudo-Rapidity η PYTHIA Tune A Min-Bias Soft + Hard.8 TeV all PT PYTHIA regulates the perturbative 2-to-2 parton-parton cross sections with cut-off parameters which allows one to run with Lots of hard scattering in P T Min-Bias (hard) > at 0. the One Tevatron! can simulate both hard and soft collisions in one program. PYTHIA Tune A CDF Run 2 Default Charged Particle Density The relative amount of hard versus soft depends on the cut-off and can be tuned. Charged Density dn/dηdφdpt (/GeV/c).0E+00.0E-0.0E-02.0E-03.0E-04.0E-05.0E-06 CDF Preliminary PT(hard) > 0 GeV/c 0 2 4 6 8 0 2 4 PT(charged) (GeV/c) Tuned to fit the CDF Run underlying event! Pythia 6.206 Set A CDF Min-Bias Data.8 TeV η < 2% of Min-Bias events have P T (hard) > 5 GeV/c! % of Min-Bias events have P T (hard) > 0 GeV/c! This PYTHIA fit predicts that 2% of all Min-Bias events are a result of a hard 2-to-2 parton-parton scattering with P T (hard) > 5 GeV/c (% with P T (hard) > 0 GeV/c)! Rick Field Florida/CDF/CMS Page 29

PYTHIA Tune A LHC Min-Bias Predictions Charged Density dn/dηdφdpt (/GeV/c).0E+00.0E-0.0E-02.0E-03.0E-04.0E-05 Charged Particle Density Pythia 6.206 Set A.8 TeV 630 GeV 50% 2% of Min-Bias events have P T (hard) > 0 GeV/c! η < % of Events 40% PT(hard) > 5 GeV/c PT(hard) > 0 GeV/c 30% 20% Hard-Scattering in Min-Bias Events Pythia 6.206 Set A 4 TeV 0% 0% 00,000 0,000 00,000 CM Energy W (GeV) LHC?.0E-06 CDF Data 0 2 4 6 8 0 2 4 % of Min-Bias events have P T (hard) > 0 GeV/c! PT(charged) (GeV/c) Shows the center-of-mass energy dependence of the charged particle density, dn chg /dηdφdp T, for Min-Bias collisions compared with PYTHIA Tune A with P T (hard) > 0. PYTHIA Tune A predicts that % of all Min-Bias events at.8 TeV are a result of a hard 2-to-2 parton-parton scattering with P T (hard) > 0 GeV/c which increases to 2% at 4 TeV! Rick Field Florida/CDF/CMS Page 30

UE Parameters ISR Parameters Intrensic KT CDF Run P (Z) T PYTHIA 6.2 CTEQ5L Parameter MSTP(8) MSTP(82) PARP(82) PARP(83) PARP(84) PARP(85) PARP(86) PARP(89) PARP(90) PARP(62) PARP(64) PARP(67) MSTP(9) PARP(9) PARP(93) Tune A 4 2.0 GeV 0.5 0.4 0.9 0.95.8 TeV 0.25.0.0 4.0.0 5.0 Tune AW 4 2.0 GeV 0.5 0.4 0.9 0.95.8 TeV 0.25.25 0.2 4.0 2. 5.0 Tune used by the CDF-EWK group! PT Distribution /N dn/dpt 0.2 0.08 0.04 0.00 Z-Boson Transverse Momentum CDF Run Data PYTHIA Tune A PYTHIA Tune AW 0 2 4 6 8 0 2 4 6 8 20 Z-Boson PT (GeV/c) CDF Run published.8 TeV Normalized to Shows the Run Z-boson p T distribution (<p T (Z)>.5 GeV/c) compared with PYTHIA Tune A (<p T (Z)> = 9.7 GeV/c), and PYTHIA Tune AW (<p T (Z)> =.7 GeV/c). Effective Q cut-off, below which space-like showers are not evolved. The Q 2 = k T2 in α s for space-like showers is scaled by PARP(64)! Rick Field Florida/CDF/CMS Page 3

Jet-Jet Correlations (DØ) Jet#-Jet#2 φ Distribution φ Jet#-Jet#2 MidPoint Cone Algorithm (R = 0.7, f merge = 0.5) L= 50 pb - (Phys. Rev. Lett. 94 2280 (2005)) Data/NLO agreement good. Data/HERWIG agreement good. Data/PYTHIA agreement good provided PARP(67) =.0 4.0 (i.e. like Tune A, best fit 2.5). Rick Field Florida/CDF/CMS Page 32

CDF Run P (Z) T PYTHIA 6.2 CTEQ5L Z-Boson Transverse Momentum UE Parameters Parameter MSTP(8) MSTP(82) PARP(82) PARP(83) PARP(84) PARP(85) Tune DW 4.9 GeV 0.5 0.4.0 Tune AW 4 2.0 GeV 0.5 0.4 0.9 PT Distribution /N dn/dpt 0.2 0.08 0.04 CDF Run Data PYTHIA Tune DW HERWIG CDF Run published.8 TeV Normalized to ISR Parameters PARP(86) PARP(89) PARP(90) PARP(62) PARP(64) PARP(67).0.8 TeV 0.25.25 0.2 2.5 0.95.8 TeV 0.25.25 0.2 4.0 0.00 0 2 4 6 8 0 2 4 6 8 20 Z-Boson PT (GeV/c) Shows the Run Z-boson p T distribution (<p T (Z)>.5 GeV/c) compared with PYTHIA Tune DW, and HERWIG. MSTP(9) PARP(9) 2. 2. PARP(93) 5.0 5.0 Intrensic KT Tune DW uses D0 s perfered value of PARP(67)! Tune DW has a lower value of PARP(67) and slightly more MPI! Rick Field Florida/CDF/CMS Page 33

All use LO α s with Λ = 92 MeV! Parameter Tune AW Tune DW Tune D6 PYTHIA 6.2 Tunes PDF CTEQ5L CTEQ5L CTEQ6L UE Parameters MSTP(8) MSTP(82) PARP(82) 4 2.0 GeV 4.9 GeV 4.8 GeV Uses CTEQ6L PARP(83) 0.5 0.5 0.5 PARP(84) PARP(85) 0.4 0.9 0.4.0 0.4.0 Tune A energy dependence! ISR Parameter PARP(86) PARP(89) 0.95.8 TeV.0.8 TeV.0.8 TeV PARP(90) 0.25 0.25 0.25 PARP(62).25.25.25 PARP(64) 0.2 0.2 0.2 PARP(67) 4.0 2.5 2.5 MSTP(9) PARP(9) 2. 2. 2. PARP(93) 5.0 5.0 5.0 Intrinsic KT Rick Field Florida/CDF/CMS Page 34

PYTHIA 6.2 Tunes All use LO α s with Λ = 92 MeV! Tune A UE Parameters ISR Parameter Tune D Intrinsic KT Parameter Tune DWT Tune D6T ATLAS PDF CTEQ5L CTEQ6L CTEQ5L MSTP(8) MSTP(82) 4 4 4 PARP(82).9409 GeV.8387 GeV.8 GeV PARP(83) 0.5 0.5 0.5 PARP(84) 0.4 0.4 0.5 Tune AW Tune B PARP(85) These are Tune BW.0 old PYTHIA.0 6.2 0.33 tunes! There are new 6.420 tunes by PARP(86).0.0 0.66 PARP(89) Peter Skands.96 TeV (Tune.96 S320, TeV update.0 TeV of S0) PARP(90) 0.6 0.6 0.6 Peter Skands (Tune N324, N0CR) PARP(62).25.25.0 Hendrik Hoeth (Tune P329, Professor ) PARP(64) 0.2 0.2.0 PARP(67) 2.5 2.5 MSTP(9) PARP(9) Tune 2. DW 2. PARP(93) 5.0 5.0.0.0 Tune D6 5.0 ATLAS energy dependence! Tune D6T Rick Field Florida/CDF/CMS Page 35

JIMMY Runs with HERWIG and adds multiple parton interactions! The Energy in the Underlying Event in High P T Jet Production JIMMY: MPI J. M. Butterworth J. R. Forshaw M. H. Seymour Proton Underlying Event Outgoing Parton Jet # Direction Toward Away Final-State Radiation <Densities> vs P T (jet#) JIMMY at CDF φ Outgoing Parton PT(hard) PT(JIM)= 2.5 GeV/c. PT(JIM)= 3.25 GeV/c. "Transverse" ETsum Density (GeV) "Transverse" PTsum Density: dpt/dηdφ JMRAD(9).6 =.8 JIMMY Default "Transverse" PTsum Density (GeV/c) 4.0 3.0 2.0.0.2 0.8 0.4 0.0.96 TeV.96 TeV "Transverse" ETsum Density: det/dηdφ JIMMY Default CDF Run 2 Preliminary generator level theory 0 00 200 300 400 500 HW JM325 The Drell-Yan JIMMY 0.0 Tune PTJIM = 3.6 GeV/c, JMRAD(73) =.8 Initial-State Radiation AntiProton Underlying Event CDF Run 2 Preliminary generator level theory PT(particle jet#) (GeV/c) JM325 PY Tune A PY Tune A Charged Particles ( η <.0, PT>0.5 GeV/c) 0 50 00 50 200 250 300 350 400 450 500 HW PT(particle jet#) (GeV/c) JIMMY was tuned to fit the energy density in the transverse region for leading jet events! "Leading Jet" MidPoint R = 0.7 η(jet) < 2 All Particles ( η <.0) "Leading Jet" MidPoint R = 0.7 η(jet) < 2 Rick Field Florida/CDF/CMS Page 36

Highest p T charged particle! PTmax Direction φ Correlations in φ Min-Bias Associated Charged Particle Density Charged Particle Density 0.5 0.4 0.3 0.2 0. 0.0 CDF Preliminary data uncorrected Charged Particle Density: dn/dηdφ Charge Density Min-Bias PTmax 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Associated Density PTmax not included Associated densities do not include PTmax! Charged Particles ( η <.0, PT>0.5 GeV/c) Use the maximum p T charged particle in the event, PTmax, to define a direction and look at the the associated density, dnchg/dηdφ, in min-bias collisions (p T > 0.5 GeV/c, η < ). Shows the data on the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events. Also shown is the average charged particle density, dnchg/dηdφ, for min-bias events. Rick Field Florida/CDF/CMS Page 37

Highest p T charged particle! PTmax Direction φ Correlations in φ Min-Bias Associated Charged Particle Density Charged Particle Density 0.5 0.4 0.3 0.2 0. 0.0 CDF Preliminary data uncorrected Charged Particle Density: dn/dηdφ Charge Density Min-Bias 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Use the maximum p T charged particle in the event, PTmax, to define a direction and look at the the associated It is more probable density, dnchg/dηdφ, to find a particle in min-bias collisions (p T > 0.5 GeV/c, η < ). accompanying PTmax than it is to find a particle in the central region! Shows the data on the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events. Also shown is the average charged particle density, dnchg/dηdφ, for min-bias events. PTmax Associated Density PTmax not included Associated densities do not include PTmax! Charged Particles ( η <.0, PT>0.5 GeV/c) Rick Field Florida/CDF/CMS Page 38

Min-Bias Associated Charged Particle Density Rapid rise in the particle density in the transverse region as PTmax increases! PTmax Direction Jet # φ Toward φ Correlations in φ Away Jet #2 Ave Min-Bias 0.25 per unit η-φ Associated Particle Density.0 0.8 0.6 0.4 0.2 0.0 PTmax > 2.0 GeV/c PTmax >.0 GeV/c PTmax > 0.5 GeV/c Associated Particle Density: dn/dηdφ Transverse Region PTmax not included Charged Particles ( η <.0, PT>0.5 GeV/c) PTmax 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) CDF Preliminary data uncorrected Transverse Region Min-Bias PTmax > 2.0 GeV/c PTmax > 0.5 GeV/c Shows the data on the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events with PTmax > 0.5,.0, and 2.0 GeV/c. Shows jet structure in min-bias collisions (i.e. the birth of the leading two jets!). Rick Field Florida/CDF/CMS Page 39

Highest p T charged particle! PTmax Direction φ Correlations in φ Min-Bias Associated Charged PTsum Density Charged PTsum Density (GeV/c) 0.5 0.4 0.3 0.2 0. 0.0 CDF Preliminary data uncorrected Charged PTsum Density: dpt/dηdφ PTsum Density Min-Bias PTmax 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Associated Density PTmax not included Associated densities do not include PTmax! Charged Particles ( η <.0, PT>0.5 GeV/c) Use the maximum p T charged particle in the event, PTmax, to define a direction and look at the the associated PTsum density, dptsum/dηdφ. Shows the data on the φ dependence of the associated charged PTsum density, dptsum/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events. Also shown is the average charged particle density, dptsum/dηdφ, for min-bias events. Rick Field Florida/CDF/CMS Page 40

Min-Bias Associated Charged PTsum Density Rapid rise in the PTsum density in the transverse region as PTmax increases! PTmax Direction Jet # φ Toward φ Correlations in φ Away Jet #2 Ave Min-Bias 0.24 GeV/c per unit η-φ Associated PTsum Density (GeV/c).0 0.8 0.6 0.4 0.2 0.0 Associated PTsum Density: dpt/dηdφ PTmax > 2.0 GeV/c PTmax >.0 GeV/c PTmax > 0.5 GeV/c Transverse Region PTmax not included PTmax Transverse Region 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) CDF Preliminary data uncorrected Charged Particles ( η <.0, PT>0.5 GeV/c) Min-Bias Shows the data on the φ dependence of the associated charged PTsum density, dptsum/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events with PTmax > 0.5,.0, and 2.0 GeV/c. Shows jet structure in min-bias collisions (i.e. the birth of the leading two jets!). Rick Field Florida/CDF/CMS Page 4

Min-Bias Associated Charged Particle Density PTmax > 2.0 GeV/c PTmax Direction Toward φ Correlations in φ Away φ PTmax > 0.5 GeV/c Associated Particle Density.0 0.8 0.6 0.4 0.2 0.0 Associated Particle Density: dn/dηdφ PTmax > 2.0 GeV/c PY Tune A PTmax > 0.5 GeV/c PY Tune A Transverse Region 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) PY Tune A CDF Preliminary data uncorrected theory + CDFSIM PY Tune A.96 TeV Transverse Region PTmax PTmax not included ( η <.0, PT>0.5 GeV/c) Shows the data on the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events with PTmax > 0.5 GeV/c and PTmax > 2.0 GeV/c compared with PYTHIA Tune A (after CDFSIM). PYTHIA Tune A predicts a larger correlation than is seen in the min-bias data (i.e. Tune A min-bias is a bit too jetty ). Rick Field Florida/CDF/CMS Page 42

PTmax Direction Toward φ Correlations in φ Away PTmax > 2.0 GeV/c φ PTmax > 0.5 GeV/c Min-Bias Associated Charged PTsum Density Associated PTsum Density (GeV/c).0 0.8 0.6 0.4 0.2 0.0 Associated PTsum Density: dpt/dηdφ PTmax > 2.0 GeV/c PY Tune A PTmax > 0.5 GeV/c PY Tune A Transverse Region PTmax not included PTmax 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) PY Tune A CDF Preliminary data uncorrected theory + CDFSIM PY Tune A.96 TeV Transverse Region ( η <.0, PT>0.5 GeV/c) Shows the data on the φ dependence of the associated charged PTsum density, dptsum/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events with PTmax > 0.5 GeV/c and PTmax > 2.0 GeV/c compared with PYTHIA Tune A (after CDFSIM). PYTHIA Tune A predicts a larger correlation than is seen in the min-bias data (i.e. Tune A min-bias is a bit too jetty ). Rick Field Florida/CDF/CMS Page 43

Charged Particle Density 0.0.0 0. 0.0 Associated Charged Particle Density: dn/dηdφ RDF Preliminary py Tune A generator level PTmax > 5.0 GeV/c Min-Bias.96 TeV Toward Region PTmax >.0 GeV/c 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Min-Bias Associated Charged Particle Density PTmax > 0.0 GeV/c PTmax > 2.0 GeV/c PTmax > 0.5 GeV/c Charged Particles ( η <.0, PT>0.5 GeV/c) PTmax Direction Toward Away φ Shows the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events at.96 TeV with PTmax > 0.5,.0, 2.0, 5.0, and 0.0 GeV/c from PYTHIA Tune A (generator level). PTmax Direction φ Toward Away Shows the associated charged particle density in the toward, away and transverse regions as a function of PTmax for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) for min-bias events at.96 TeV from PYTHIA Tune A (generator level). Rick Field Florida/CDF/CMS Page 44

Charged Particle Density 0.0.0 0. 0.0 Associated Charged Particle Density: dn/dηdφ RDF Preliminary py Tune A generator level PTmax > 5.0 GeV/c Min-Bias.96 TeV Toward Region PTmax >.0 GeV/c 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Min-Bias Associated Charged Particle Density PTmax > 0.0 GeV/c PTmax > 2.0 GeV/c PTmax > 0.5 GeV/c Charged Particles ( η <.0, PT>0.5 GeV/c) Charged Particle Density.6.2 0.8 0.4 0.0 PTmax Direction Associated Charged Particle Density: dn/dηdφ φ RDF Preliminary Min-Bias py Tune A generator level.96 TeV Toward "Toward" Away "Away" Charged Particles ( η <.0, PT>0.5 GeV/c) 0 2 4 6 8 0 2 4 6 8 20 PTmax (GeV/c) "Transverse" Shows the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events at.96 TeV with PTmax > 0.5,.0, 2.0, 5.0, and 0.0 GeV/c from PYTHIA Tune A (generator level). PTmax Direction φ Toward Away Shows the associated charged particle density in the toward, away and transverse regions as a function of PTmax for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) for min-bias events at.96 TeV from PYTHIA Tune A (generator level). Rick Field Florida/CDF/CMS Page 45

Charged Particle Density 0.0.0 0. 0.0 Associated Charged Particle Density: dn/dηdφ RDF Preliminary py Tune A generator level PTmax > 5.0 GeV/c Min-Bias.96 TeV Toward Region PTmax >.0 GeV/c 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Min-Bias Associated Charged Particle Density PTmax > 0.0 GeV/c PTmax > 2.0 GeV/c PTmax > 0.5 GeV/c Charged Particles ( η <.0, PT>0.5 GeV/c) Charged Particle Density 2.5.6 2.0.2.5 0.8.0 0.4 0.5 PTmax Direction Associated Charged Particle Density: dn/dηdφ φ RDF RDF Preliminary Min-Bias Preliminary Min-Bias 4 TeV.96 TeV Toward py Tune A generator level py Tune generator level "Toward" "Toward" Away "Away" Charged Charged Particles Particles ( η <.0, ( η <.0, PT>0.5 PT>0.5 GeV/c) GeV/c) 0.0 0 2 54 6 0 8 0 5 2 4 20 6 8 25 20 PTmax (GeV/c) "Away" "Transverse" "Transverse" Shows the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events at.96 TeV with PTmax > 0.5,.0, 2.0, 5.0, and 0.0 GeV/c from PYTHIA Tune A (generator level). PTmax Direction φ Toward Away Shows the associated charged particle density in the toward, away and transverse regions as a function of PTmax for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) for min-bias events at.96 TeV from PYTHIA Tune A (generator level). Rick Field Florida/CDF/CMS Page 46

Charged Particle Density 0.0.0 0. 0.0 Associated Charged Particle Density: dn/dηdφ RDF Preliminary py Tune A generator level PTmax > 5.0 GeV/c Min-Bias.96 TeV Toward Region PTmax >.0 GeV/c 0 30 60 90 20 50 80 20 240 270 300 330 360 φ (degrees) Min-Bias Associated Charged Particle Density PTmax > 0.0 GeV/c PTmax > 2.0 GeV/c PTmax > 0.5 GeV/c Charged Particles ( η <.0, PT>0.5 GeV/c) "Transverse" Charged Particle Charged Density 2.5.2.6 2.0.0.2 0.8.5 0.6 0.8 PTmax Direction "Transverse" Associated Charged Particle Density: dn/dηdφ φ RDF Preliminary Min-Bias RDF Preliminary Min-Bias Min-Bias 4 TeV 4 TeV.96 TeV Toward py Tune A generator level py Tune A generator level "Toward" "Toward" ~ factor of 2! "Away".0 "Transverse" 0.4 Away 0.4 0.5 0.2 Charged Charged Particles Particles ( η <.0, ( η <.0, PT>0.5 PT>0.5 GeV/c) GeV/c) Charged Particles ( η <.0, PT>0.5 GeV/c) 0.0 0 2 54 6 0 8 0 5 2 4 20 6 8 25 20 PTmax (GeV/c) "Away".96 TeV "Transverse" Shows the φ dependence of the associated charged particle density, dnchg/dηdφ, for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) relative to PTmax (rotated to 80 o ) for min-bias events at.96 TeV with PTmax > 0.5,.0, 2.0, 5.0, and 0.0 GeV/c from PYTHIA Tune A (generator level). PTmax Direction φ Toward Away Shows the associated charged particle density in the toward, away and transverse regions as a function of PTmax for charged particles (p T > 0.5 GeV/c, η <, not including PTmax) for min-bias events at.96 TeV from PYTHIA Tune A (generator level). Rick Field Florida/CDF/CMS Page 47

st Rick Field Talk 2 Tomorrow at :30pm st Workshop on Energy Scaling in Hadron-Hadron Collisions From Min-Bias to the Underlying Event CDF Run 2 Underlying Event Studies Comparing with the 630 GeV data Rick Field Talk 3 Wednesday at 9:00am From CDF to CMS Extrapolating to the LHC Tune S320 and P329 compared with Tune A, DW, and DWT Rick Field Florida/CDF/CMS Page 48