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LPCC - LHC Standard Model Workshop

LPCC - LHC Standard Model Workshop. Early Days of Perturbative QCD. Rick Field University of Florida. Outline. My Story of QCD. Feynman-Field Phenomenology: 1973-1983. FF1: The Black Box Model. CERN June 14, 2017. FF2: The QCD Improved Parton Model.

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LPCC - LHC Standard Model Workshop

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  1. LPCC - LHC Standard Model Workshop Early Days of Perturbative QCD Rick Field University of Florida Outline • My Story of QCD. • Feynman-Field Phenomenology: 1973-1983. • FF1: The Black Box Model. CERN June 14, 2017 • FF2: The QCD Improved Parton Model. • My talk at ICHEP78 Tokyo and my lectures at Boulder79. • The QCD Improved Parton Model: Drell-Yan Lepton-Pair Production • The QCD Improved Parton Model: Large Transverse Momentum Mesons in Hadron-Hadron Collisions. • The QCD Improved Parton Model: Jet Production in Hadron-Hadron Collisions. • From 7 GeV p0’s to 2 TeV Jets. Rick Field – Florida

  2. My Story of QCD The Quark Model The Eightfold Way QCD Theory! Parton Model + Perturbative QCD! Interacting quarks, anti-quarks, and gluons! The QCD Improved Parton Model Before we knew the partons were quarks and gluons! Non-interacting partons! Partons = quarks, anti-quarks, and glue! Still non-interacting partons! The Parton Model The Naïve Parton Model Rick Field – Florida

  3. Feynman-Field Phenomenology Toward and Understanding of Hadron-Hadron Collisions 1st hat! Feynman and Field • From 7 GeV/c p0’s to 2 TeV Jets. The early days of trying to understand and simulate hadron-hadron collisions. Rick Field – Florida

  4. The Feynman-Field Days 1973-1983 • 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). The Naïve Parton Model “Feynman-Field Jet Model” The Naïve Parton Model The Naïve Parton Model QCD Improved Parton Model QCD Improved Parton Model QCD Improved Parton Model • 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

  5. The Naïve Parton Model Electron-Positron Annihilations: Virtual Photon Born Term = Quarks interacting with photons (electromagnetic interactions) Inelastic Electron Proton Scattering: Born Term = Rick Field – Florida

  6. Naïve Parton ModelElectron-Positron Annihilations Color Factor Count the Number of Quark Flavors:Measure the ratio Rand verify that there are indeed three colors of quarks. 3 Flavors Rick Field – Florida

  7. Naïve Parton ModelElectron-Positron Annihilations Count the Number of Quark Flavors:Measure the ratio Rand verify that there are indeed three colors of quarks. The data are from ORSAY, FEASCATI, NOVOSIBIRSK, SLAC-LBL, DASP, CLEO, DHHM, CELLO, JADE, MARK J, PLUTO, and TASSO. Compiled by B. Wiik (1978). 5 Flavors: u d s c b Rick Field – Florida

  8. Naïve Parton ModelElectron-Positron Annihilations Quark Fragmentation Functions:Measure the probability of finding a hadron of type h carrying the fraction z of the parent quarks momentum. Very unlikely that a parton will give all its momentum to a single hadron! Observed by the JADE detector at PETRA at ECM = 30 GeV (1978). z Rick Field – Florida

  9. Parton Model: DIS In the early days of the Parton Model we did not know the partons were quarks, anti-quarks, and gluons! We learned this from DIS and e+e- experiments! Parton Model: Virtual photon with 4-momentum q interacting with a parton of type i with mass m and electric charge ei carrying fraction x of the proton’s 4-momentum P. (M = proton mass) Provided Q2is large! Deep Inelastic Scattering (DIS) A fast moving proton is a collection of partons(constituents of the proton) each carrying a certain fraction x = x of the proton momentum, P. is thenumber of partons of type i within a fast moving hadron of type A with fraction of momentum x (pi = xP) between x and x + dx. Scaling: Predict that the DIS structure functions are not a function of both n and Q2, but are simply a function of the parton scaling variable, x. Also predict: Momentum Sum Rule:The sum of the momentum of all the constituents must equal one. Rick Field – Florida

  10. Naïve Parton Model: DIS A fast moving proton is a collection of partons(quarks, anti-quarks, and gluons) each carrying a certain fraction x of the proton momentum, P. Inelastic Electron-Proton Scattering: Net Number of Quarks:The net number of u quarks in a proton is 2 and the net number of d quarks is 1. DIS Experiments (1972-1975): Observe approximate scaling and measure quark distributions. Find that only about one-half of the proton momentum is carried by the charged quarks: The remaining momentum must be carried by electrically neutral partons (i.e.gluons). Rick Field – Florida

  11. Naïve Parton Model: DIS Quarks have fractional electric charge: By comparing deep inelastic electron-proton scattering with deep inelastic neutrino-proton scattering one can determine the electric charge of the quarks. Parton Distribution Functions (PDF’s)! Inelastic Electron-Proton Scattering: Rick Field 1976 Inelastic Neutrino-Proton Scattering: Rick Field – Florida

  12. The Naïve Parton Model Quarks interacting with W & Z (weak interactions) Inelastic Neutrino Proton Scattering: Born Term = Quarks interacting with photons (electromagnetic interactions) Drell-Yan Muon-Pair Production: Born Term = Rick Field – Florida

  13. The Naïve Parton Model Large Transverse Meson Production in Hadron-Hadron Collisions Quark-Quark Elastic Scattering Born Term = Quarks interacting with quarks (strong interactions) What do I do now?? Field-Feynman Black-Box Model Rick Field – Florida

  14. Hadron-Hadron Collisions FF1 1977 • 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

  15. Quark-Quark Black-Box Model No gluons! FF1 1977 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

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

  17. 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

  18. ICHEP 1978 Tokyo Dynamics of High Energy Reactions • The Effective Strong Interaction Coupling Constant, as(Q2), and the Mass Scale L. Rick Field California Institute of Technology (Plenary talk presented at the XIX International Conference on High Energy Physics, Tokyo, Japan) The QCD Parton Model Approach - Outline of Talk R. D. Field ICHEP78 • Quark and Gluon Distributions within Hadrons: Scale Breaking. • Analysis of ep and mp Data. • Analysis of F2 and xF3 in Neutrino Processes. • Large pT Production of Mesons and Jets in pp Collisions. • Scale Breaking Effects: Eds/d3p. • Correlations – Evidence for Gluons. • The Jet Cross Section.. • Muon-Pair Production in pp Collisions. • QCD Factorization – “Constant” Pieces. • Large pT Muon-Pair Production. • “Scaling” in pp →m+m- +X. • A Look to the Future. • pp → p0 +X at W = 500 GeV. • Large pT Charm Production. • gg→ Jet + Jet and e+e-→ e+e-+Jet+Jet. • Three Jets: e+e-→ q+qbar+Jet and pp→Jet+Jet+Jet+X.. • Quark and Gluon Fragmentation Functions: Scale Breaking. • Gluon Jets. Rick Field – Florida

  19. QCD Improved Parton Model Drell-Yan Muon-Pair Production Born Amplitude = Born Term = “Born” Include Leading Order QCD Corrections (Order as) “Annihilation” “Annihilation” Virtual Corrections “Compton” “Compton” Rick Field – Florida

  20. R. Field ICHEP78 R. D. Field ICHEP78 • The distribution in transverse momentum, pT, of the m+m- pair produced in pp collisions at W = 27.4 GeV together with the QCD perturbative predictions. The “Compton” and “annihilation” contributions are given by the dashed and dotted curves, respectively. Rick Field 1978 Rick Field – Florida

  21. QCD Improved Parton Model Real Gluon Emissions Order as Born Term Plus Virtual Gluon Emissions Order as Total Cross-Section Order as Finite = Infinite + Infinite Total Cross-Section Leading Order Rick Field – Florida

  22. Intrinsic Parton kT Parton Intrinsic (Primordial) Transverse Momentum: From the uncertainty principle one expects that the partons will have some intrinsic (primordial) transverse momentum. Expect intrinsic kT(P→q) ≈ 200 – 300 MeV/c! Transverse size of the proton. Jet Size: Also expect that the hadrons within a jet will have some intrinsic transverse momentom. Expect intrinsic kT(q→h) ≈ 200 – 300 MeV/c! Rick Field – Florida

  23. Primordial kT Smearing Intrinsic Primordial transverse momentum! Finite Finite Rick Field – Florida

  24. R. Field ICHEP78 Early Experimental Test of QCD R. D. Field ICHEP78 Large primordial kT! • The distribution in transverse momentum, pT, of the m+m- pair produced in pp collisions at W = 27.4 GeV together with the QCD perturbative prediction folded with a Gaussian primordial parton momentum spectrum with <kT> = 600 MeV (solid curve). The dashed curve results from the parton primordial motion only with no perturbative QCD terms. Rick Field 1978 Rick Field – Florida

  25. R. Field ICHEP78 The data are from D. C. Horn et al., Phys. Rev. Letters 36, 1239 (1976) and 37, 1374 (1976); S. W. Herb et al., Phys. Rev. Letters 39, 352 (1977); W. R. Innes et al., Phys. Rev. Letters 39, 1240 (1977); also see the talk by L. Lederman at this conference. Early Experimental Test of QCD W = 27.4 GeV W = 19.4 GeV • Energy dependence of the large pT tail expected for pp -> m+m- + X from the QCD perturbative prediction folded with a Gaussian primordial parton momentum spectrum with <kT> = 600 MeV. • Data on the energy dependence of the <pT> of the m+m- pair in proton-nucleon collisions which indicate that the pT distribution is becoming broader as the energy increases. Rick Field – Florida

  26. Naïve Parton Model External Variables (neglect the mass of A, B, and h) A+B→h+X Internal-External Connection a+b→c+d Internal Variables (neglect masses) Rick Field – Florida

  27. Naïve Parton Model A+B→h+X External Variables Internal Variables xb = 1 zc = 1 zc = 1 Rick Field – Florida

  28. QCD Parton-Parton Scattering Large Transverse Meson Production in Hadron-Hadron Collisions Include All The QCD 2-to-2 Parton-Parton Processes (Order as2) Parton = quark, anti-quark, & gluon QCD effective coupling (5) (1) (6) (2) (7) (3) (8) (4) (9) Rick Field – Florida

  29. Parton Model Scaling Quark-Quark Elastic Scattering Sum over final-state spins and color. Average over initial-state spins and color. Parton Model Scaling Constant at fixed qcm and xT! (provided the PDF’s and the fragmentation functions scale and as is constant) Rick Field – Florida

  30. Parton Model Scaling Large Transverse Meson Production in Hadron-Hadron Collisions Include All The QCD 2-to-2 Parton-Parton Processes (Order as2) (5) (1) k = 1 to 9 (6) (2) (7) (3) (8) (4) (9) = Constant at fixed qcm and xT! (provided the PDF’s and the fragmentation functions scale and as is constant) Parton Model Scaling Rick Field – Florida

  31. High pTp-Meson Production The FNAL data (open squares) are from J. W. Cronin et al. (CP Collaboration), Phys. Rev. D11 (1975); D. Antreasyan et al., Phys. Rev. Letters 38 (1977); Phys. Rev. Letters 38 (1977). The FNAL data at W = 19.4 GeV(solid triangles) are from G. Donaldson et al., Phys Rev. Letters 36 (1976). The FNAL data (open circles) are from D. C. Carey et al., Fermilab Report FNAL-PUB-75120-EXP (1975). High pT Data 1977 The ISR data (solid dots) are from B. Alper et al. (BS Collaboration), Nucl. Phys. B100 (1975). The ISR data (crosses) are from F. W. Busser et al., Nucl. Phys. B106 (1976). Yikes!! The data is behaving like 1/pT8 not 1/pT4 at fixed xT. W = 19.4 GeV xT = 0.2 W = 53 GeV xT = 0.2 Rick Field – Florida

  32. FF1: Black-Box Model FF1 (1977) QCD N = 2 FF1 N = 4 CIM N = 4 Naïve Parton-Parton Black-Box Model Rick Field – Florida

  33. CIM Model Constituent Interchange Model (CIM) Meson-Quark Scattering Meson within the proton! D. Sivers, S. J. Brodsky, and R. Blankenbecler, Phys. Reports 23C, 1 (1976); R. Blankenbecler, S. J. Brodsky, and J. F. Gunion, “The Magnitudes of Large Transverse Momentum Cross Sections”, SLAC-PUB-2057 (1977) Rick Field – Florida

  34. QCD Improved Parton Model Large Transverse Meson Production in Hadron-Hadron Collisions Quark-Quark Elastic Scattering Include Leading Order QCD 2-to-2 Parton-Parton Processes (Order as2) Parton = quark, anti-quark, & gluon Sum over final-state spins and color. Average over initial-state spins and color. Rick Field – Florida

  35. QCD Improved Parton Model Use the “renormalization group improved” PDF’s from DIS and “renormalization group improved” fragmentation functions from e+e- annihilations and the running QCD coupling! A+B→h+X Renormalization Group Improved PDF’s! Renormalization Group Improved Fragmentation! QCD effective coupling Running QCD Effective Coupling! Q2 dependent PDF’s! Q2 dependent fragmentation! Rick Field – Florida

  36. QCD Improved Parton Model Large Transverse Meson Production in Hadron-Hadron Collisions QCD effective coupling Include All The QCD 2-to-2 Parton-Parton Processes (Order as2) (5) (1) k = 1 to 9 (6) (2) (7) (3) Use the “renormalization group improved” PDF’s from DIS and “renormalization group improved” fragmentation functions from e+e- annihilations and the running QCD coupling! (8) (4) (9) Naïve parton model scaling is now broken! QCD Improved Parton Model Possible Choices for the Scale Rick Field – Florida

  37. R. Field ICHEP78 Primordial kT has a big effect at low pT and low W where the cross section is very steep! QCD Improved Parton Model Early Experimental Test of QCD F1 (1978) FFF2 (1978) R. D. Field ICHEP78 Large primordial kT! • Comparison of a QCD model (normalized absolutely) with data on large pT pion production in proton-proton collisions at W = 19.4 and 53 GeV with qcm = 90o. The dot-dashed and solid curves are the results before and after smearing, respectively, with L = 0.4 GeV/c and <kT>primordial = 848 MeV/c and the dashed curves are with L = 0.6 GeV/c. The contributions from quark-quark, quark-antiquark, and antiquark-antiquark (i.e. no gluons) is shown by the dotted curves. Rick Field – Florida

  38. R. Field ICHEP78 QCD Improved Parton Model F1 (1978) R. D. Field ICHEP78 Approaches a constant at large pT! • Data on pT4 times Eds/d3p for large pT pion production at qcm = 90o and fixed xT = 0.2 versus pT compared with the predictions (with absolute normalization) of a model that incorporates all the features expected from QCD. The dot-dashed and solid curves are the results before and after smearing with <kT>primordial = 848 MeV, respectively, with L = 0.4 GeV/c and the dashed curves are the results of using L = 0.6 GeV/c (after smearing). The dotted curve is pT4(1/pT8). pT4(1/pT8) Rick Field – Florida

  39. R. Field ICHEP78 QCD Improved Parton Model Early Experimental Test of QCD The ISR data (triangles) are from CERN-Columbia-Oxford-Rockefeller Experiment (CCOR), reported by L. Di Lellain the Workshop on Future ISR Experiments, September 14-21, 1977. The ISR data (open circles) are from A. G. Clark et al., Phys Letters 74B (1978) 267. Also, talk presented by A. G. Clark at this conference. FFF2 (1978) Approaches a pT4 behavior at large pT! R. D. Field ICHEP78 • Data on pT8 times Eds/d3p for large pT pion production at qcm = 90o and fixed xT = 0.2, 0.35, and 0.5 versus pT compared with the predictions (with absolute normalization) of a model that incorporates all the features expected from QCD. The dot-dashed and solid curves are the results before and after smearing with <kT>primordial = 848 MeV, respectively, with L = 0.4 GeV/c and the dashed curves are the results of using L = 0.6 GeV/c (after smearing). Recent data from ISR (triangles, open circles) show a deviation from a horizontal straight line (1/pT8) behavior as expected from QCD. Rick Field – Florida

  40. R. Field ICHEP78 QCD Improved Parton Model Early QCD Predictions R. Field ICHEP78 R. D. Field ICHEP78 • The behavior of pT8 times the 90o single p0 cross section, Eds/d3p, at xT = 0.05 versus pT calculated from the QCD approach with L = 0.4 GeV/c (solid curves) and L = 0.6 GeV/c (dashed curves). The two low pT data points are at 53 and 63 GeV. The predictions are a factor of 100 (1000) times larger than the flat horizontal (1/pT8) extrapolation to W = 500 GeV (1000 GeV). Rick Field – Florida

  41. CDF Run 2 Data Charged Particle Production Measurement of Particle Production and Inclusive Differential Cross Sections in Proton-Antiproton Collisions at 1.96 TeV, CDF Collaboration, Phys. Rev. D79, 112005 (2009) W = 1.96 TeV xT = 0.05 Rick Field – Florida

  42. R. Field BND 2016 Amazing! I was right! W = 1960 108 factor of ≈ 10,000 50 Rick Field – Florida

  43. QCD “Jet” Production A+B→c+X QCD Improved Parton Model Large Transverse Momentum Parton Production Rick Field – Florida

  44. R. Field ICHEP78 QCD Improved Parton Model Early QCD Predictions R. D. Field ICHEP78 • Comparison of the results on the 90op0 cross section, Eds/d3p, from the QCD approach with L = 0.4 GeV/c (solid curves) and the quark-quark “black-box” parton model of FF1 (dotted curves). Both models agree with the data at W = 53 GeV. The QCD approach results in much larger cross sections than the FF1 model at W = 500 and 1000 GeV. The FF1 results at 1000 GeV (not shown) are only slightly larger than at 500 GeV. Also shown are the cross sections for producing a jet at 90o (divided by 1000) as predicted by the QCD approach (dashed curves) and the FF1 model (dot-dashed curve) 30 GeV/c Jets! Rick Field – Florida

  45. R. Field ICHEP78 QCD Improved Parton Model Early Experimental Test of QCD R. D. Field ICHEP78 The FNAL data (E260) are from C. Bromberg et al., Phys Rev Letters 38 (1977); C. Bromberg et al., CALT-68-613 (to be published in Nucl. Phys.). The FNAL data (E395) are from the Fermilab-Lehigh-Pennsylvania-Wisconsin Collaboration, talk given by W. Selove at this conference. 6 GeV/c Jets! • Comparison of the jet and single p0 cross sections measured at 200 GeV (W = 19.4 GeV) and qcm = 90o. The jet data are from two FNAL experiments, E260 and E395, where a jet is defined as the sum of all the particles into their respective detectors. Also shown is the QCD prediction for the cross section of producing a parton (quark, antiquark, or gluon) at W = 19.4 GeV and qcm = 90o. FFF2 (1978) Rick Field – Florida

  46. 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

  47. Boulder 1979 • The NATO Advanced Institute on Quantum Flavordynamics, Quantum Chromodynamics, and Unified Theories, held at the University of Colorado, Boulder, Colorado, July 9 – 27, 1979. (NATO Advanced Institute Series B: Physics, Volume 24, Plenum Press, 1980) Lecturers G. Altarelli A. J. Buras C. De Tar S. Ellis R. D. Field D. Gross C. H. Llewellyn Smith J. Wess Rick Field Boulder 1979 Jimmie Field Boulder 1979 Rick Field – Florida

  48. R. Field Boulder 1979 CIM versus the QCD Improved Parton Model p-+p→p± + X The data are from H. J. Frisch, Precise Measurement of the High pT Single Particle Spectra in p-p Collisions at Fermilab (E258), talk presented at the XIV Moriond Conference (1979).. At low xT the dominate QCD sub-process is gluon production which fragments equally into p+ and p-! Direct CIM Contribution p-+ d-quark → p- + d-quark To produce an outgoing p+ in the CIM approach one must find a p+ within the incoming p- or the incoming proton (with small probability)! Rick Field – Florida

  49. Boulder 1979 R. Field Boulder 1979 • The NATO Advanced Institute on Quantum Flavordynamics, Quantum Chromodynamics, and Unified Theories, held at the University of Colorado, Boulder, Colorado, July 9 – 27, 1979. 40 TeV 2 TeV 400 GeV/c Jets! 30 GeV/c Jets! Rick Field – Florida

  50. R. Field BND 2016 CDF (2006) R. Field Boulder 1979 1.96 TeV Amazing! I was right! 27 Years! 2 TeV 400 GeV/c Jets! Rick Field – Florida

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