Introduction to Elementary Particles

David Griffiths is Professor of Physics at the Reed College in Portland, Oregon. After obtaining his PhD in elementary particle theory at Harvard, he taught at several colleges and universities before joining the faculty at Reed in 1978. He specializes in classical electrodynamics and quantum mechanics as well as elementary particles, and has written textbooks on all three subjects.

"I'd recommend this book to anyone in the field and anyone lecturing in it. It's wonderful. Reading any section will always yield insights, and you can't go wrong with Griffiths as a guide." (Times Higher Education Supplement, December 2009)"A clearly written textbook balancing intuitive understanding and mathematical rigour, emphasizing elementary particle theory." (Reviews, May 2009)

• Preface to the First Edition ixPreface to the Second Edition xiFormulas and Constants xiiiIntroduction 11 Historical Introduction to the Elementary Particles 131.1 The Classical ERA (1897–1932) 131.2 The Photon (1900–1924) 151.3 Mesons (1934–1947) 181.4 Antiparticles (1930–1956) 201.5 Neutrinos (1930–1962) 231.6 Strange Particles (1947–1960) 301.7 The Eightfold Way (1961–1964) 351.8 The Quark Model (1964) 371.9 The November Revolution and Its Aftermath (1974–1983 and 1995) 441.10 Intermediate Vector Bosons (1983) 471.11 The Standard Model (1978–?) 492 Elementary Particle Dynamics 592.1 The Four Forces 592.2 Quantum Electrodynamics (QED) 602.3 Quantum Chromodynamics (QCD) 662.4 Weak Interactions 712.4.1 Neutral 722.4.2 Charged 742.4.2.1 Leptons 742.4.2.2 Quarks 752.4.3 Weak and Electromagnetic Couplings of W and Z 782.5 Decays and Conservation Laws 792.6 Unification Schemes 843 Relativistic Kinematics 893.1 Lorentz Transformations 893.2 Four-vectors 923.3 Energy and Momentum 963.4 Collisions 1003.4.1 Classical Collisions 1003.4.2 Relativistic Collisions 1013.5 Examples and Applications 1024 Symmetries 1154.1 Symmetries, Groups, and Conservation Laws 1154.2 Angular Momentum 1204.2.1 Addition of Angular Momenta 1224.2.2 Spin 1/2 1254.3 Flavor Symmetries 1294.4 Discrete Symmetries 1364.4.1 Parity 1364.4.2 Charge Conjugation 1424.4.3 CP 1444.4.3.1 Neutral Kaons 1454.4.3.2 CP Violation 1474.4.4 Time Reversal and the TCP Theorem 1495 Bound States 1595.1 The Schrödinger Equation 1595.2 Hydrogen 1625.2.1 Fine Structure 1655.2.2 The Lamb Shift 1665.2.3 Hyperfine Splitting 1675.3 Positronium 1695.4 Quarkonium 1715.4.1 Charmonium 1745.4.2 Bottomonium 1755.5 Light Quark Mesons 1765.6 Baryons 1805.6.1 Baryon Wave Functions 1815.6.2 Magnetic Moments 1895.6.3 Masses 1916 The Feynman Calculus 1976.1 Decays and Scattering 1976.1.1 Decay Rates 1976.1.2 Cross Sections 1996.2 The Golden Rule 2036.2.1 Golden Rule for Decays 2046.2.1.1 Two-particle Decays 2066.2.2 Golden Rule for Scattering 2086.2.2.1 Two-body Scattering in the CM Frame 2096.3 Feynman Rules for a Toy Theory 2116.3.1 Lifetime of the A 2146.3.2 A + A → B + B Scattering 2156.3.3 Higher-order Diagrams 2177 Quantum Electrodynamics 2257.1 The Dirac Equation 2257.2 Solutions to the Dirac Equation 2297.3 Bilinear Covariants 2357.4 The Photon 2387.5 The Feynman Rules for QED 2417.6 Examples 2457.7 Casimir’s Trick 2497.8 Cross Sections and Lifetimes 2547.9 Renormalization 2628 Electrodynamics and Chromodynamics of Quarks 2758.1 Hadron Production in e+e− Collisions 2758.2 Elastic Electron–Proton Scattering 2798.3 Feynman Rules For Chromodynamics 2838.4 Color Factors 2898.4.1 Quark and Antiquark 2898.4.2 Quark and Quark 2928.5 Pair Annihilation in QCD 2948.6 Asymptotic Freedom 2989 Weak Interactions 3079.1 Charged Leptonic Weak Interactions 3079.2 Decay of the Muon 3109.3 Decay of the Neutron 3159.4 Decay of the Pion 3219.5 Charged Weak Interactions of Quarks 3249.6 Neutral Weak Interactions 3299.7 Electroweak Unification 3389.7.1 Chiral Fermion States 3389.7.2 Weak Isospin and Hypercharge 3429.7.3 Electroweak Mixing 34510 Gauge Theories 35310.1 Lagrangian Formulation of Classical Particle Mechanics 35310.2 Lagrangians in Relativistic Field Theory 35410.3 Local Gauge Invariance 35810.4 Yang–Mills Theory 36110.5 Chromodynamics 36610.6 Feynman Rules 36910.7 The Mass Term 37210.8 Spontaneous Symmetry-breaking 37510.9 The Higgs Mechanism 37811 Neutrino Oscillations 38711.1 The Solar Neutrino Problem 38711.2 Oscillations 39011.3 Confirmation 39211.4 Neutrino Masses 39511.5 The Mixing Matrix 39712 Afterword: What’s Next? 40112.1 The Higgs Boson 40112.2 Grand Unification 40512.3 Matter/Antimatter Asymmetry 40912.4 Supersymmetry, Strings, Extra Dimensions 41112.4.1 Supersymmetry 41112.4.2 Strings 41312.5 Dark Matter/Dark Energy 41412.5.1 Dark Matter 41412.5.2 Dark Energy 41612.6 Conclusion 417A The Dirac Delta Function 423B Decay Rates and Cross Sections 429B.1 Decays 429B.1.1 Two-body Decays 429B.2 Cross Sections 430B.2.1 Two-body Scattering 430C Pauli and Dirac Matrices 433C.1 Pauli Matrices 433C.2 Dirac Matrices 434D Feynman Rules (Tree Level) 437D.1 External Lines 437D.2 Propagators 437D.3 Vertex Factors 438Index 441