Elementary Particle Physics: An Intuitive Introduction

Description

This modern introduction to particle physics equips students with the skills needed to develop a deep and intuitive understanding of the physical theory underpinning contemporary experimental results. The fundamental tools of particle physics are introduced and accompanied by historical profiles charting the development of the field. Theory and experiment are closely linked, with descriptions of experimental techniques used at CERN accompanied by detail on the physics of the Large Hadron Collider and the strong and weak forces that dominate proton collisions. Recent experimental results are featured, including the discovery of the Higgs boson. Equations are supported by physical interpretations, and end-of-chapter problems are based on datasets from a range of particle physics experiments including dark matter, neutrino, and collider experiments. A solutions manual for instructors is available online. Additional features include worked examples throughout, a detailed glossary of key terms, appendices covering essential background material, and extensive references and further reading to aid self-study, making this an invaluable resource for advanced undergraduates in physics. Half Title page Title page Copyright page Dedication Contents Preface Overview of This Book Acknowledgements 1 Introduction 1.1 A Brief History of Forces 1.2 The Standard Model of Particle Physics 1.3 The Large Hadron Collider 1.4 Units of Particle Physics and Dimensional Analysis Exercises 2 Special Relativity 2.1 Symmetries and Their Consequences 2.1.1 Rotational Invariance 2.1.2 Relativistic Invariance 2.1.3 Applying Relativity 2.2 Relativistic Wave Equations 2.2.1 The Klein–Gordon Equation 2.2.2 The Dirac Equation 2.2.3 Electromagnetism Exercises 3 A Little Group Theory 3.1 Groups as Symmetries 3.2 The Rotation Group 3.2.1 Two-Dimensional Rotations: SO(2) 3.2.2 Three-Dimensional Rotations: SO(3) 3.2.3 SO(3), SU(2), and Spin 3.3 Isospin and the Quark Model 3.3.1 Isospin 3.3.2 What is a “Particle”? 3.3.3 The Quark Model 3.4 Why the Photon Has Two Polarizations Exercises 4 Fermi’s Golden Rule and Feynman Diagrams 4.1 Invitation: The Barn 4.2 Scattering Systematics 4.2.1 The Scattering Cross Section 4.2.2 Fermi’s Golden Rule 4.3 Feynman Diagrams 4.3.1 Diagrams in Physics: Circuits 4.3.2 Diagrams in Physics: Electron–Muon Scattering 4.3.3 Feynman Diagrams: Summary 4.3.4 Feynman Diagrams: Caveat Emptor Exercises 5 Particle Collider Experiment 5.1 Before Collision: Particle Acceleration 5.2 At Collision: Particle Detection 5.3 Detector Coordinates 5.4 Detector Components 5.4.1 Tracking System 5.4.2 Calorimetry 5.4.3 Muon System 5.4.4 Unobservable Neutrinos 5.5 After Collision: Triggering and Data Acquisition 5.6 Statistical Analyses 5.6.1 Statistical Uncertainties 5.6.2 Derivation of Poisson Distribution 5.6.3 Significance and Discovery Exercises 6 Quantum Electrodynamics in e+e− Collisions 6.1 e+e− → μ+μ− 6.1.1 Solutions to the Massless Dirac Equation 6.1.2 Helicity Configurations 6.1.3 Calculating the Cross Section 6.1.4 Inclusive Cross Sections 6.1.5 Exclusive Cross Sections 6.2 e+e− → Hadrons 6.2.1 Inclusive Hadronic Cross Sections 6.2.2 Properties of the Inclusive Cross Section: Color 6.2.3 Properties of the Inclusive Cross Section: Spin Exercises 7 Quarks and Gluons 7.1 Crossing Symmetry 7.1.1 Electron–Quark Scattering 7.2 Deeply Inelastic Scattering 7.2.1 Physical Interpretation of Bjorken Scaling 7.3 Three-Jet Events 7.3.1 The Glue That Binds the Proton 7.3.2 External Gluon Wavefunction 7.3.3 Fermion Propagator 7.3.4 The Cross Section for e+e− → qqg 7.3.5 Tests of a Spin-1 Gluon 7.4 Spinor Helicity Exercises 8 Quantum Chromodynamics 8.1 Color Symmetry 8.2 Non-Abelian Gauge Theory 8.2.1 Covariant Derivative 8.2.2 Connections and Curvature 8.3 Consequences of Quantum Chromodynamics 8.3.1 Masslessness of the Gluon 8.3.2 Gluon Degrees of Freedom 8.3.3 Self-Interaction of the Gluon 8.3.4 The Running Coupling and Asymptotic Freedom 8.3.5 Low-Energy QCD Exercises 9 Parton Evolution and Jets 9.1 Scale Transformations 9.1.1 Scale Invariance of QCD 9.1.2 Fractals and Scale Invariance 9.2 Parton Evolution 9.2.1 Collinear Divergences in QCD 9.2.2 Energy Dependence of Parton Distributions 9.2.3 Physical Interpretation of the DGLAP Equations 9.3 Jets 9.3.1 All-Orders Predictions: Thrust Exercises 10 Parity Violation 10.1 Decay of the Neutron 10.2 Discrete Lorentz Transformations 10.2.1 Parity Transformations 10.2.2 Time Reversal and Charge Conjugation 10.2.3 CPT Theorem 10.3 Parity Violation in Nuclear Decays 10.3.1 Consequences of Parity Violation 10.4 The V − A Theory 10.4.1 Decay of the Muon Exercises 11 The Mass Scales of the Weak Force 11.1 Problems with the V − A Theory 11.2 Spontaneous Symmetry Breaking 11.2.1 Quantum Mechanics Analogy 11.2.2 Goldstone’s Theorem for the Mexican Hat Potential 11.2.3 Higgs Mechanism in Superconductivity 11.3 Electroweak Unification 11.3.1 Properties of the Weak Force Carriers 11.3.2 Spontaneous Breaking of Electroweak Symmetry 11.3.3 The Broken Weak Theory 11.3.4 Four Predictions of the Broken Weak Theory Exercises 12 Consequences of Weak Interactions 12.1 Flavor Mixing in the Weak Interactions 12.2 The Weak Interactions in the Quark Sector: CP Violation 12.2.1 Weak Interactions of Charged Leptons 12.2.2 Weak Interactions of Quarks 12.2.3 CP Violation of the Weak Interactions 12.2.4 Fermion Masses in the Standard Model and Tests of Unitarity 12.2.5 CP Violation and the Early Universe: Sakharov Conditions 12.3 The Weak Interactions in the Lepton Sector: Neutrino Mixing 12.3.1 Neutrino Oscillations 12.3.2 Neutrino Oscillation Measurement 12.3.3 Neutrino Astrophysics Exercises 13 The Higgs Boson 13.1 Searching for the Higgs Boson at LEP 13.1.1 e+e− → Z 13.1.2 e+e− → H 13.1.3 e+e− → ZH 13.2 Searching for the Higgs Boson at Tevatron and LHC 13.2.1 pp → H 13.2.2 pp → H → W+W− 13.2.3 The Golden Channels: pp → H → γγ and pp → H → 4ℓ 13.3 Properties of the Higgs Boson 13.3.1 Scalar Potential Coupling λ 13.3.2 Coupling Strength Proportional to Mass 13.3.3 Spin-0 Exercises 14 Particle Physics at the Frontier 14.1 Neutrino Masses 14.2 Dark Matter 14.3 Higgs Self-Coupling 14.4 End of Feynman Diagrams? 14.4.1 Failure of Convergence of Feynman Diagrams 14.4.2 More Efficient Calculational Techniques 14.5 The Future of Collider Physics 14.5.1 International Linear Collider (ILC) 14.5.2 Circular Electron Positron Collider (CEPC) 14.5.3 Future Circular Collider (FCC) Exercises Appendix A Useful Identities Appendix B Review of Quantum Mechanics Appendix C Particle Physics Jargon Glossary Bibliography Index