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.

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 Higgs Hunter's Guide is a definitive and comprehensive guide to the physics of Higgs bosons. In particular, it discusses the extended Higgs sectors required by those recent theoretical approaches that go beyond the Standard Model, including supersymmetry and superstring-inspired models.

Recent results of the top-quark search by CDF and D0 at the Tevatron showed the existence of the sixth quark--the top quark. The measured mass was 176 " 8 " 10 GeV from CDF and 19921{sup +19} " 22 GeV from D0. The standard model (SM) that was proposed more than 20 years ago is confirmed to a solid ground as all the ingredients were found, except for electroweak symmetry breaking (EWSB). The understanding of EWSB is necessary to explain all fermion and gauge boson masses on a fundamental level. The authors propose the study of four-top, t{bar t}t{bar t}, production at hadronic supercolliders as a probe to electroweak symmetry breaking.