Presentation on theme: "May 2005CTEQ Summer School1 Global Analysis of QCD and Parton Distribution Functions Dan Stump Department of Physics and Astronomy Michigan State University."— Presentation transcript:
May 2005CTEQ Summer School1 Global Analysis of QCD and Parton Distribution Functions Dan Stump Department of Physics and Astronomy Michigan State University Ref: Pumplin, Stump, Huston, Lai, Nadolsky, Tung, New generation of parton distributions with uncertainties from global QCD analysis, JHEP07 (2002) 012.
May 2005CTEQ Summer School2 “QCD is our most perfect physical theory.” -- Frank Wilczek F. Wilczek, Nuclear Physics A663&664 (2000) 3c-20c.
May 2005CTEQ Summer School3 High energy particles interact through their quark and gluon constituents – the partons. Asymptotic freedom : the parton cross sections can be approximated by perturbation theory. Factorization theorem : Parton distribution functions of the nucleon are the link between the PQCD theory and measurements on nucleons.
May 2005CTEQ Summer School4 Motivations for global analysis of QCD the deep structure of the nucleon testing QCD – gluon radiation, higher order perturbation theory, the value of S The PDF’s are needed to calculate cross sections for scattering processes at the LHC; the search for new physics.
May 2005CTEQ Summer School5 The goals of QCD global analysis are to construct accurate PDF’s; to know the uncertainties of the PDF’s; to enable predictions, including uncertainties.
May 2005CTEQ Summer School6 The parton model and global analysis of QCD --- inclusive scattering processes
May 2005CTEQ Summer School7 Outline 1/ Introduction 2/ Experiments 3/ Methods of Analysis 4/ Results
May 2005CTEQ Summer School8 PDF’s from Global Analysis QCD Theory LO, NLO, NNLO MS-bar factorization DGLAP evolution Data DIS (H1, ZEUS, BCDMS, NMC, CCFR) DY (E605, E866) High ET jets (CDF, D0) W asymmetry (CDF) S (M Z ) Phenomenology CTEQ, MRST, Alekhin, GGK, H1, ZEUS, …
May 2005CTEQ Summer School10 The HERA e ± p collider
May 2005CTEQ Summer School11 Theory of deep-inelastic electron scattering + corrections
May 2005CTEQ Summer School12 H1 collaboration at HERA Data used in the CTEQ6 analysis… DIS e + p e + X @ low-x 104 points DIS e + p e + X @ high-x 126 points … published 2000, 2001
May 2005CTEQ Summer School13 ZEUS collaboration at HERA Data used in the CTEQ6 analysis … DIS e + p e + X 229 points … published 2001
May 2005CTEQ Summer School14 BCDMS collaboration DIS +p +X339 points DIS +d +X251 points Bologna - CERN - Dubna - Munich - Saclay NA4 muon scattering experiment at CERN History: 1976 (C. Rubbia) to 1994 Homework Problem -- Why was scattering used? Why is d an interesting contrast to p?
May 2005CTEQ Summer School15 NMC collaboration at CERN DIS +p +X201 points DIS +d +X123 points … published 1997 The kinematic range 0.0001 < x < 0.7 and 0.01< Q 2 < 70 GeV 2 is covered.
May 2005CTEQ Summer School16 CCFR collaboration In the CTEQ6 analysis, number of data points = 156; from publications of 1997 and 2001 Chicago Columbia Fermilab Rochester The Lab E neutrino experiments at Fermilab (E744 in 1985; and E770 in 1987-88). Measurements of F 2 (x,Q 2 ) and xF 3 (x,Q 2 ) for and DIS Homework Problem: What do we learn from neutrino/antineutrino scattering that we don’t know from electron scattering?
May 2005CTEQ Summer School17 Theory of deep-inelastic neutrino scattering
May 2005CTEQ Summer School18 Experiment E605 For CTEQ6 : 119 data points The Drell-Yan process
May 2005CTEQ Summer School19 The Drell-Yan process — lepton pair production in hadron collisions
May 2005CTEQ Summer School20 The Drell-Yan process Experiment E866 Homework Question: E866 measured the asymmetry of down and up anti-quarks in the nucleon sea using Drell-Yan di-muons produced in 800 GeV proton interactions with hydrogen and deuterium targets. How does it work? … using 800 GeV protons from the Tevatron The NuSea Collaboration
May 2005CTEQ Summer School21 FNAL E866 – the NuSea Collaboration Homework Problem: How does this experiment tell us about the light-quark flavor asymmetry in the nucleon sea?
May 2005CTEQ Summer School22 Inclusive jet production at the Tevatron collider CDF collaboration: 33 data points at central rapidity (-0.7 < < 0.7) D0 collaboration: 90 data points in five rapidity bins (-3 < < 3)
May 2005CTEQ Summer School23 D0 Collaboration, Inclusive jet production in ppbar collisions, PRL 86, 1707 (2001).
May 2005CTEQ Summer School24 D0 Collaboration, Inclusive jet production in ppbar collisions, PRL 86, 1707 (2001).
May 2005CTEQ Summer School25 Lepton charge asymmetry from W + /W - production (CDF collaboration) Homework Problem: What can the asymmetry A tell us about the PDF’s?
May 2005CTEQ Summer School26 CDF Collaboration, Measurement of the lepton charge asymmetry in W boson decays produced by ppbar collisions, PRL 81, 5754 (1998).