Introduction to High Energy Physics 4th Edition

1 Quarks and leptons 1 1.1 Preamble 1 1.2 The Standard Model of particle physics 7 1.3 Particle classification: fermions and bosons 12 1.4 Particles and antiparticles 13 1.5 Free particle wave equations 16 1.6 Helicity states: helicity conservation 19 1.7 Lepton flavours 20 1.8 Quark flavours 22 1.9 The cosmic connection 26 Problems 33 2 Interactions and fields 35 2.1 Classical and quantum pictures of interactions 35 2.2 The Yukawa theory of quantum exchange 36 2.3 The boson propagator 37 2.4 Feynman diagrams 38 2.5 Electromagnetic interactions 40 2.6 Renormalisation and gauge invariance 42 2.7 Strong interactions 43 2.8 Weak and electroweak interactions 46 2.9 Gravitational interactions 51 2.10 The interaction cross-section 51 2.11 Decays and resonances 55 Problems 61 v vi Contents 3 Invariance principles and conservation laws 63 3.1 Translation and rotation operators 63 3.2 The parity operation 65 3.3 Pion spin and parity 66 3.4 Parity of particles and antiparticles 69 3.5 Tests of parity conservation 72 3.6 Charge conjugation invariance 73 3.7 Charge conservation and gauge invariance 75 3.8 Baryon and lepton conservation 79 3.9 C PT invariance 81 3.10 C P violation and T violation 81 3.11 Neutron electric dipole moment 83 3.12 Isospin symmetry 87 3.13 Isospin in the two-nucleon and pion–nucleon systems 88 3.14 Isospin, strangeness and hypercharge 91 Problems 93 4 Quarks in hadrons 95 4.1 Charm and beauty; the heavy quarkonium states 95 4.2 Comparison of quarkonium and positronium levels 102 4.3 The baryon decuplet 109 4.4 Quark spin and colour 114 4.5 The baryon octet 115 4.6 Quark–antiquark combinations: the light pseudoscalar mesons 118 4.7 The light vector mesons 121 4.8 Other tests of the quark model 123 4.9 Mass relations and hyperfine interactions 126 4.10 Electromagnetic mass differences and isospin symmetry 129 4.11 Magnetic moments of baryons 130 4.12 Mesons built of light and heavy quarks 132 4.13 The top quark 134 Problems 139