Introduction to QCD slides - P.Hoyer.pdf - High Energy Physics Group

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Quarks are for real: Pointlike scattering of electrons High energy electrons scatter from pointlike quarks inside the proton: e +q → e +q (in analogy to Rutherford’s experiment) The struck quark flies out of the proton and “hadronizes” into a spray (jet) of hadrons (mostly pions). At relativistic energies quark-antiquark pairs are created to ensure that all quarks end up as constituents of mesons or baryons. Deep Inelastic Scattering (DIS): e + p → e + anything SLAC 1969: Ee = 20 GeV Paul Hoyer Mugla 2010 14
Paul Hoyer Mugla 2010 The search for asymptotic freedom The SLAC data (1969) showed that the proton charge is located in apparently free, pointlike constituents, presumably the quarks proposed earlier based on the hadron spectrum. This raised the question: “How can the quarks be nearly free inside the proton, yet bind so strongly together that they do not exist as free particles?” It was known that the coupling strength of QED “runs”, ie., α = α(Q 2 ) increases as the distance scale r = 1/Q decreases. If there were theories where α = α(Q 2 ) decreases with r this might explain the SLAC data. α(r) e p QED γ * e q π ... p 15 log(r)
Page 1 and 2: Paul Hoyer Mugla 2010 Introduction
Page 3 and 4: Paul Hoyer Mugla 2010 The Discovery
Page 5 and 6: Paul Hoyer Mugla 2010 The Pion as a
Page 7 and 8: Matter field: Paul Hoyer Mugla 2010
Page 9 and 10: a a Fundamental Representation: ! F
Page 12 and 13: Mesons Paul Hoyer Mugla 2010 Quark
Page 20 and 21: Paul Hoyer Mugla 2010 Quantum Chrom
Page 22 and 23: Paul Hoyer Mugla 2010 Asymptotic Fr
Page 24 and 25: Paul Hoyer Mugla 2010 Puzzles of QC
Page 26 and 27: Instantaneous Coulomb interaction P
Page 28 and 29: Binding energy [meV] 0 -1000 -3000
Page 30 and 31: Paul Hoyer Mugla 2010 Origin of the
Page 32 and 33: √+%&'( !"#$$%$&'()#*%+,-. !" # !"
Page 34 and 35: Paul Hoyer Mugla 2010 34 P. Skands
Page 36 and 37: Paul Hoyer Mugla 2010 The accuracy
Page 38: dσ dX Factorization Theorem Factor
Page 41 and 42: ξ = 1 + = log E + p � � m 2 +
Page 43 and 44: :02 PM e + e - Paul Hoyer Mugla 201
Page 45 and 46: No exclusive amplitudes for charged
Page 47 and 48: Unitarity (white): σtot(s) = � P
Page 49 and 50: Paul Hoyer Mugla 2010 Optical Theor
Page 51 and 52: e�nition Paul Hoyer Mugla 2010 In
Page 53: Cross σσ Sections at NNLO X+1 (R)
Page 56 and 57: Paul Hoyer Mugla 2010 QCD is very s
Page 58 and 59: Measurement of quark and gluon colo
Page 60 and 61: Paul Hoyer Mugla 2010 The CDF Detec
Page 62 and 63: Paul Hoyer Mugla 2010 pp - → jet

Introduction to QCD slides - P.Hoyer.pdf - High Energy Physics Group

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