The Search For Electroweak Symmetry Breaking

This book presents an introduction to the physics of electroweak symmetry breaking. The techniques necessary for discovering the Higgs boson and elucidating its properties are examined. Models with non-minimal Higgs sectors, including supersymmetric models are discussed, along with models where there is no Higgs boson and the symmetry breaking occurs in a strongly interacting sector.

This is an expanded version of the report by the Electroweak Symmetry Breaking and Beyond the Standard Model Working Group which was contributed to Particle Physics ? Perspectives and Opportunities, a report of the Division of Particles and Fields Committee for Long Term Planning. One of the Working Group's primary goals was to study the phenomenology of electroweak symmetry breaking and attempt to quantify the ?physics reach? of present and future colliders. Their investigations encompassed the Standard Model ? with one doublet of Higgs scalars ? and approaches to physics beyond the Standard Model. These include models of low-energy supersymmetry, dynamical electroweak symmetry breaking, and a variety of extensions of the Standard Model with new particles and interactions. The Working Group also considered signals of new physics in precision measurements arising from virtual processes and examined experimental issues associated with the study of electroweak symmetry breaking and the search for new physics at present and future hadron and lepton colliders.This volume represents an important contribution to the efforts being made to advance the frontiers of particle physics.

Contents:Quark Mixing and CP Violation (F J Gilman)Heavy Quark Effective Theory (A V Manohar)Introduction to Low-Energy Supersymmetry (G F Giudice)An Introduction to Dynamical Electroweak Symmetry Breaking (R S Chivukula)Hadron Colliders, the Top Quark, and the Higgs Sector (C Quigg)Physics Potential of LEP2 and NLC (R Miquel)Precision Tests of the Electroweak Theory (P Langacker) Readership: High energy physicists. Keywords:

The electroweak theory unifies two basic forces of nature: the weak force and electromagnetism. This 2007 book is a concise introduction to the structure of the electroweak theory and its applications. It describes the structure and properties of field theories with global and local symmetries, leading to the construction of the standard model. It describes the particles and processes predicted by the theory, and compares them with experimental results. It also covers neutral currents, the properties of W and Z bosons, the properties of quarks and mesons containing heavy quarks, neutrino oscillations, CP-asymmetries in K, D, and B meson decays, and the search for Higgs particles. Each chapter contains problems, stemming from the long teaching experience of the author, to supplement the text. This will be of great interest to graduate students and researchers in elementary particle physics.

This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence of the Higgs boson, a weakly interacting spin-zero particle that is the agent of electroweak symmetry breaking, the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the TeV energy scale. Indirect constraints from global analyses of electroweak measurements suggest that the mass of the standard-model Higgs boson is less than 200 GeV. Once its mass is assumed, the properties of the Higgs boson follow from the electroweak theory, and these inform the search for the Higgs boson. Alternative mechanisms for electroweak symmetry breaking are reviewed, and the importance of electroweak symmetry breaking is illuminated by considering a world without a specific mechanism to hide the electroweak symmetry. For all its triumphs, the electroweak theory has many shortcomings.

The LHC is expected to fid new physics beyond the Standard Model (BSM). Technicolor models are a class of BSM models which involve a new strongly interacting sector responsible for electroweak symmetry breaking (EWSB). The phenomenological viability of these models depends on features such as the existence of an infrared fixed point (IRFP) at strong coupling, and the size of the mass anomalous dimension at this fixed point. As these features are at strong coupling they are not accessible to perturbative methods, and so need to be investigated non-perturbatively using lattice methods. In this thesis, two candidate Technicolor theories are investigated using two independent and complementary lattice methods, the Schrodinger Functional (SF) and the Monte Carlo Renormalisation Group (MCRG), to measure the running of the coupling and the anomalous mass dimension in these theories.