The Higgs Boson Discovery at the Large Hadron Collider (Springer Tracts in Modern Physics Book 264)

This book provides a comprehensive overview of the field of Higgs boson physics. It offers the first in-depth review of the complete results in connection with the discovery of the Higgs boson at CERN’s Large Hadron Collider and based on the full dataset for the years 2011 to 2012. The fundamental concepts and principles of Higgs physics are introduced and the important searches prior to the advent of the Large Hadron Collider are briefly summarized. Lastly, the discovery and first mensuration of the observed particle in the course of the CMS experiment are discussed in detail and compared to the results obtained in the ATLAS experiment. Acknowledgments 6 Contents 7 1 Introduction 10 1.1 The Standard Model of Particle Physics 10 1.2 The Problem of Massive Particles in the Standard Model 15 1.3 Synopsis and Guideline to the Book 17 References 21 2 The Higgs Boson in the Standard Model of Particle Physics 23 2.1 The Principle of Gauge Symmetries 23 2.1.1 Extension to Non-Abelian Gauge Symmetries 26 2.2 The Electroweak Gauge Theory 31 2.2.1 Extension to a Theory of Electroweak Interactions 33 2.3 Electroweak Symmetry Breaking and the Higgs Boson 40 2.3.1 The Goldstone Model 40 2.3.2 Extension to a Gauge Theory 42 2.4 The Electroweak Sector of the Standard Model of Particle Physics 44 2.4.1 Custodial Symmetry 48 2.4.2 Giving Masses to Fermions 51 2.4.3 Summary and Conclusions 55 References 59 3 Higgs Boson Searches Before the Advent of the Large Hadron Collider 60 3.1 Constraints Within the Theory 60 3.1.1 The Unitarity Bound 62 3.1.2 The Goldstone Potential at Higher Orders 64 3.2 Indirect Constraints from Electroweak Precision Measurements 67 3.2.1 Electroweak Precision Observables 67 3.2.2 Statistical Model 69 3.2.3 Results of the Likelihood Analysis 72 3.3 Direct Searches at the Large Electron Positron Collider 75 3.3.1 Statistical Framework 76 3.3.2 Direct Search Results 81 3.4 Direct Searches at the Tevatron Proton Anti-Proton Collider 83 References 85 4 Discovery of the Higgs Boson at the Large Hadron Collider 87 4.1 Setting up the Scene for Discovery 87 4.1.1 The Large Hadron Collider 87 4.1.2 Main Experiments and Event Reconstruction 89 4.1.3 First Measurements of Known Standard Model Processes 95 4.2 The Eve of the Hunt for the Higgs Boson 98 4.2.1 Decay Channels and Production Modes 98 4.2.2 First Searches and Statistical Methods 102 4.3 The Discovery of a New Particle in the Bosonic Decay Channels 105 4.3.1 The Signal in the Hrightarrowγγ Decay Channel 108 4.3.2 The Signal in the HrightarrowZZ Decay Channel 114 4.3.3 Evidence of the Signal in the HrightarrowWW Decay Channel 120 4.3.4 Conclusions on the Bosonic Decay Channels 126 4.4 Signs of the New Particle in the Fermionic Decay Channels 128 4.4.1 The Coupling to Leptons 129 4.4.2 The Coupling to Quarks 141 4.4.3 Conclusions on the Coupling to Fermions 152 References 154 5 Properties of the New Particle 157 5.1 Mass and Decay Width of the New Particle 157 5.1.1 Canonical Estimate of the Mass and Decay Width 157 5.1.2 Decay Width Estimate from the Off-Shell Cross Section 161 5.2 Spin and CP Symmetry 167 5.2.1 Groundwork for Spin and CP Analyses 167 5.2.2 Estimate of Spin and CP in the HrightarrowZZ Decay Channel 170 5.3 Coupling Structure 175 5.3.1 Prerequisite Studies 175 5.3.2 Statistical Model 178 5.3.3 Test of the Coupling Structure 180 References 186 6 Conclusions 188 References 192 Front Matter....Pages i-ix Introduction....Pages 1-13 The Higgs Boson in the Standard Model of Particle Physics....Pages 15-51 Higgs Boson Searches Before the Advent of the Large Hadron Collider....Pages 53-79 Discovery of the Higgs Boson at the Large Hadron Collider....Pages 81-150 Properties of the New Particle....Pages 151-181 Conclusions....Pages 183-187