We study the phenomenology of a hypercharge-zero SU(2) triplet scalar whose existence is motivated by two-step electroweak symmetry-breaking. We consider both the possibility that the triplets are stable and contribute to the dark matter density, or that they decay via mixing with the standard model Higgs boson. The former is constrained by disappearing charged track searches at the LHC and by dark matter direct detection experiments, while the latter is constrained by existing multilepton collider searches. We find that a two-step electroweak phase transition involving a stable triplet with a negative quadratic term is ruled out by direct detection searches, while an unstable triplet with a mass less than $230\ \mathrm{GeV}$ is excluded at $95\%$ confidence level.
We present a comparative study of radiative electroweak symmetry breaking and conventional standard model breaking, and pose the question whether experiments can distinguish one breaking mode from the other. The importance of the problem lies in the fact that the two breaking modes have very different physical interpretations concerning the mechanism of spontaneous electroweak symmetry breaking and the origin of mass.
We review the possibilities that the Kaluza-Klein excitations of graviton states induce electroweak symmetry breaking and that electroweak symmetry breaking could have a large impact on KK phenomenology.
We introduce the idea of bosonic see-saw mechanism in analogy with the see-saw mechanism. Bosonic see-saw is a new symmetry breaking mechanism and we apply it to explain electroweak symmetry breaking as an inevitable consequence of supersymmetry breaking. The breaking of electroweak symmetry occurs at tree level once supersymmetry is broken. Absence of color/charge breaking in this model is related to doublet-triplet splitting in grand unified theory. An extension of MSSM with a weak triplet shows very interesting results especially when mu =0. It provides the most natural understanding of why…
The problem of electroweak symmetry breaking is reviewed with discussion of future relevant experimentation at LHC and $e^+e^-$ linear colliders. The possibility of strong electroweak symmetry breaking is examined in more detail, using the BESS (Breaking Electroweak Symmetry Strongly) model as a basis for the discussion. The formal constructions are briefly presented and the possible expectations at future colliders are summarized.
We introduce in an arbitrary supersymmetric version of the standard model without elementary scalars a logarithmic operator which is irrelevant in the limit in which all symmetries are respected. However through a dynamical mechanism of the Nambu Jona Lasinio type this operator may produce two fermion vacuum condensates that may account for electroweak and contribute to supersymmetry breaking. Some of the phenomenological consequences of this set-up are discussed.
These three lectures review the state of our understanding of electroweak interactions and the search for the agent of electroweak symmetry breaking. The themes of the lectures are (i) the electroweak theory and its experimental status, (ii) the standard-model Higgs boson, and (iii) aspects of electroweak theory beyond the standard SU(2)_L x U(1)_Y model.
This review provides an elementary discussion of electroweak symmetry breaking in the minimal and the next-to-minimal supersymmetric models with the focus on the fine-tuning problem -- the tension between natural electroweak symmetry breaking and the direct search limit on the Higgs boson mass. Two generic solutions of the fine-tuning problem are discussed in detail: models with unusual Higgs decays; and models with unusual pattern of soft supersymmetry breaking parameters.
With the recent discovery of a heavy top quark $(m_t \approx 175 - 200$ GeV), the top quark opens an window to electroweak symmetry breaking. We propose the study of four-top, $t\bar t t\bar t$, production at hadronic supercolliders as a probe to electroweak symmetry breaking.
We review the mechanism of radiative electroweak symmetry breaking taking place in SUSY versions of the standard model. We further discuss different proposals for the origin of SUSY-breaking and the corresponding induced SUSY-breaking soft terms. Several proposals for the understanding of the little hierarchy problem are critically discussed.
In this talk I discuss theories of dynamical electroweak symmetry breaking, with emphasis on the implications of a heavy top-quark on the weak-interaction $ρ$ parameter.
The Higgs boson offers a unique window to hidden sector fields S_i, singlets under the Standard Model gauge group, via the renormalizable interactions |H|^2 S_i^2. We prove that such interactions can provide new patterns for electroweak breaking, including radiative breaking by dimensional transmutation consistent with LEP bounds, and trigger the strong enough first order phase transition required by electroweak baryogenesis.
We study the impact of LEP2 constraints on the dimensionless coefficients of the electroweak chiral Lagrangian on the precision observables using the improved renormalization group equations. We find that the current uncertainty in the triple and quartic gauge boson couplings can accommodate electroweak symmetry breaking models with $S(Λ=1 \textrm{TeV}) > 0$.
We investigate scenarios in which electroweak baryogenesis can occur during an exotic stage of electroweak symmetry breaking in the early Universe. This transition is driven by the expectation value of a new electroweak scalar instead of the standard Higgs field. A later, second transition then takes the system to the usual electroweak minimum, dominated by the Higgs, while preserving the baryon asymmetry created in the first transition. We discuss the general requirements for such a two-stage electroweak transition to be suitable for electroweak baryogenesis and present a toy model that illus…
We review the status of models of electroweak symmetry breaking in a slice of anti--de Sitter space. These models can be thought of as dual to strongly interacting theories of the electroweak scale. After an introduction to some generic issues in bulk theories in AdS5, we concentrate on the model-building of the Higgs sector.
We argue that classical scale invariance provides a technically natural solution to the problem of the radiative stability of the electroweak scale. Some realistic electroweak scale-invariant models are considered and their possible manifestations at the LHC are briefly discussed.
We hypothesise that all electroweak symmetry breaking terms such as fermion masses and the W and Z gauge boson masses arise radiatively from just one explicit symmetry breaking term in the Lagrangian. Our hypothesis is motivated by the lack of experimental support and the lack of predictivity of the standard symmetry breaking scenario. We construct a simple model which illustrates our ideas. We also discuss the possible importance of scale invariance.
Within the framework of gauge mediated supersymmetry breaking, we consider an electroweak symmetry breaking pattern in which there is no conventional $μ$ term. The pattern is made appealing through realizing it as low energy effective description of a supersymmetric Yang-Mills theory which is of confinement. Phenomenological implications are discussed.
We analyze the incidence on polarized $e^-e^-$ scattering of the trilinear and quartic anomalous gauge couplings which arise in the realm of a non-linear realization of electroweak symmetry breaking.
We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e+e- linear colliders are discussed.
We review the status of and recent developments in dynamical electroweak symmetry breaking, concentrating on the ideas of technicolour and top quark condensates. The emphasis is on the essential physical ideas and experimental implications rather than on detailed mathematical formalism.
Within an AdS/CFT inspired model of electroweak symmetry breaking the effects of various boundary terms and modifications to the background are studied. The effect on the S precision parameter is discussed with particular attention to its sign and whether the theory is unitary when S<0. Connections between the various possible AdS slice models of symmetry breaking are discussed.
We formulate the equivalence between the longitudinal weak-boson and the Goldstone boson as a criterion for sensitively probing the electroweak symmetry breaking mechanism and develop a precise power counting rule for chiral Lagrangian formulated electroweak theories. With these we semi-quatitatively analyze the sensitivities to various effective operators related to electrowaeak symmetry breaking via weak-boson scatterings at the CERN Large Hadron Collider (LHC).
We argue that a strongly first order electroweak phase transition is natural in the presence of strong symmetry-breaking interactions, such as technicolor. We demonstrate this using an effective linear scalar theory of the symmetry-breaking sector.
We construct and analyze an ultraviolet extension of a model in which electroweak symmetry breaking is due to both technifermion and top-quark condensates. The model includes dynamical mechanisms for all of the various gauge symmetry breakings. We discuss certain aspects in which it requires additional ingredients to be more realistic.
The physics potential of a high-energy photon collider is reviewed. The emphasis is put on aspects related to the symmetry breaking sector, including Higgs searches and production of longitudinal vector bosons.
We discuss the phenomenology of models of dynamical electroweak symmetry breaking which attempt to generate the observed fermion mass spectrum. After briefly describing the variety of and constraints on proposed models, we concentrate on the signatures of colored pseudo-Nambu-Goldstone bosons and resonances at existing and proposed colliders. These particles provide a possibly unique signature: strongly produced resonances associated with electroweak symmetry breaking. (This is the subgroup report for the ``Electroweak Symmetry Breaking and Beyond the Standard Model" working group of the DPF L…
Severe constraints on parameters of the minimal supersymmetric standard model follow from a dynamical electroweak symmetry breaking mechanism dominated by top and stop loops. In particular, the lightest Higgs boson mass is expected to be smaller than 100 GeV.
We briefly review the recent developments of probing the electroweak symmetry breaking mechanism at high energy colliders such as the CERN LEP2, the Fermilab Tevatron, the CERN LHC and the e(+)e(-) linear colliders. Both weakly interacting and strongly interacting electroweak symmetry breaking mechanisms are concerned.
We discuss the mechanism for electroweak symmetry breaking in supersymmetric versions of the standard model. After briefly reviewing the possible sources of supersymmetry breaking, we show how the required pattern of symmetry breaking can automatically result from the structure of quantum corrections in the theory. We demonstrate that this radiative breaking mechanism works well for a heavy top quark and can be combined in unified versions of the theory with excellent predictions for the running couplings of the model. (To be published in ``Perspectives in Higgs Physics'', G. Kane editor.)
In this review we discuss theories of the electroweak symmetry breaking sector in which the $W$ and $Z$ interactions become strong at an energy scale not larger than a few TeV.
Dynamical breaking of the electroweak theory, i.e. technicolor, is an intriguing extension of the Standard Model. Recently new models have been proposed featuring walking dynamics for a very low number of techniflavors. These technicolor extensions are not ruled out by current precision measurements. Here I first motivate the idea of dynamical electroweak symmetry breaking and then summarize some of the properties of the recent models and their possible cosmological implications.
In this talk we review the physics of top-quark mass generation in models of dynamical electroweak symmetry breaking and the constraints on this physics arising from limits on the deviation of the weak interaction $ρ$-parameter from one. We then discuss top-color assisted technicolor in this context.
In this note I provide a brief description of models of dynamical electroweak symmetry breaking, including walking technicolor, top-color assisted technicolor, the top-quark seesaw model, and little higgs theories.
An introduction to the physics of electroweak symmetry breaking is given. We discuss Higgs boson production in $e^+e^-$ and hadronic collisions and survey search techniques at present and future accelerators. Indirect limits on the Higgs boson mass from triviality arguments, vacuum stability, and precision electroweak measurements are presented. An effective Lagrangian, valid when there is no low mass Higgs boson, is used to discuss the physics of a strongly interacting electroweak symmetry breaking sector. Finally, the Higgs bosons of the minimal supersymmetric model are considered, along wit…
We revisit in some more detail a recent specific proposal for the breaking of the electroweak symmetry and of supersymmetry by a compact extra dimension. Possible mass terms for the Higgs and the matter hypermultiplets are considered and their effects on the spectrum analyzed. Previous conclusions are reinforced and put on firmer ground.
In this talk we survey the SSC and LHC signals and backgrounds for the physics of electroweak symmetry breaking. We study the process $pp \rightarrow WWX$ and compute the rate for the ``gold-plated'' signals $W^\pm \rightarrow \ell^\pm ν$ and $Z \rightarrow \ell^+\ell^-$ $(\ell = e,μ)$ for a wide variety of models. We use a forward jet tag and central jet veto to suppress the standard-model backgrounds. In this way we estimate the SSC and LHC sensitivities to the physics of electroweak symmetry breaking.
The origin of the fermion generations is discussed. A strong interactions spin $I_{S}$ is introduced which unifies the quarks and leptons as two multiplets of this spin. The electroweak vector bosons and gluons emerge as the fused states of these fermion multiplets.
The mechanism behind Electroweak Symmetry Breaking (EWSB) and the nature of dark matter (DM) are currently among the most important issues in high energy physics. Since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter i…
Invited talk presented at the Workshop on Physics at Current Accelerators and the Supercollider, Argonne, Illinois, and at the 17th Johns Hopkins Workshop on Current Problems in Particle Theory, Budapest, Hungary.
The study of a EW theory without spontaneous symmetry breaking is presented. A new symmetry breaking, axial-vector symmetry breaking, is found. M^{2}_{W}=1/2g^{2}m^{2}_{t}, m^{2}_{Z}=ρm^{2}_{W}/cos^{2} θ, and G_{F}=1/(2\sqrt{2}m^{2}_{t}) are obtained and they agree with data. It has been proved that the theory is renormalizable and unitary.
We argue that theories of strong electroweak symmetry breaking sector necessarily contain new spin 0 states at the TeV scale in the tbar-t and tbar-b/bbar-t channels, even if the third generation quarks are not composite at the TeV scale. These states couple sufficiently strongly to third generation quarks to have significant production at LHC via gg \to X or gb \to X. The existence of narrow resonances in QCD suggests that the strong electroweak breaking sector contains narrow resonances that decay to tbar-t or tbar-b/bbar-t, with significant branching fractions to 3 or more longitudinal W an…
In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.
In this talk we survey the SSC signals and backgrounds for the physics of electroweak symmetry breaking. We study the process $pp \rightarrow WWX$ and compute the rate for the ``gold-plated'' signals $W^\pm \rightarrow \ell^\pm ν$ and $Z \rightarrow \ell^+\ell^-$ $(\ell = e,μ)$ for a wide variety of models. We use a forward jet tag and central jet veto to suppress the standard-model backgrounds. In this way we estimate the SSC sensitivity to the physics of electroweak symmetry breaking. (Revised version contains style file ichep.sty.)
We examine the Higgs mass parameters and electroweak symmetry breaking in supersymmetric orbifold field theories in which the 4-dimensional Higgs fields originate from higher-dimensional gauge supermultiplets. It is noted that such gauge-Higgs unification leads to a specific boundary condition on the Higgs mass parameters at the compactification scale, which is independent of the details of supersymmetry breaking mechanism. With this boundary condition, phenomenologically viable parameter space of the model is severely constrained by the condition of electroweak symmetry breaking for supersymm…
`Little Higgs' models, in which the Higgs particle arises as a pseudo-Goldstone boson, have a natural mechanism of electroweak symmetry breaking associated with the large value of the top quark Yukawa coupling. The mechanism typically involves a new heavy SU(2)_{L} singlet top quark, T. We discuss the relationship of the Higgs boson and the two top quarks. We suggest experimental tests of the Little Higgs mechanism of electroweak symmetry breaking using the production and decay of the T at the Large Hadron Collider.
We review Electroweak breaking in warped Extra Dimensions and show how it is constrained by Electroweak precision tests. We then proceed to describe a model which is based on a bulk Higgs field and a metric that is deformed from the usual five dimensional Anti de Sitter space near the Infrared (IR) boundary. It allows to softly decouple the Higgs field from the Kaluza Klein excitations near the IR and thus reduces their contribution to the precision observables.
We formulate the equivalence theorem as a theoretical criterion for sensitively probing the electroweak symmetry breaking mechanism, and develop a precise power counting method for the chiral Lagrangian formulated electroweak theories. Armed with these, we perform a systematic analysis on the sensitivities of the scattering processes $W^\pm W^\pm \rightarrow W^\pm W^\pm$ and $q\bar{q}'\rightarrow W^\pm Z$ for testing all possible effective bosonic operators in the chiral Lagrangian formulated electroweak theories at the CERN Large Hadron Collider (LHC). The analysis shows that these two kinds …
After briefly remarking on alternatives for breaking the electroweak symmetry, I discuss the implication that recent precision experiments at LEP have for the symmetry breaking sector. The difficulties associated with generating fermion masses when the electroweak symmetry is broken dynamically are exposed and an alternative to the walking technicolor - extended technicolor scenario is suggested, based on models of substructure. Failures and lessons from trying to incorporate families and mixing in these latter schemes are also discussed.
Dynamical symmetry breaking provides a possible solution to the electroweak hierarchy problem. It requires new strong interactions that are effective at some high-energy scale. If there is no light Higgs boson, this scale is constrained to be in the TeV range, and signals of the new interactions can be observed, directly or indirectly, in collider experiments. Even if no observable states in the Higgs sector are kinematically accessible, a Linear Collider will cover the low-energy parameter space that arises in a systematic model-independent analysis of dynamical electroweak symmetry breaking.
We present a brief review of recent attempts to construct effective theories to describe the breaking of the electroweak symmetry in extensions of the Standard Model with new strongly interacting dynamics around the TeV scale. Particular attention is devoted to the analogies of Higgsless models with Chiral Perturbation Theory (the low-energy limit of QCD).
I give a pedagogical introduction to the physics of electroweak symmetry breaking and the uses of effective field theory in the context of Higgs physics. Higgs boson production and decay at the LHC and the consistency of the Higgs measurements with triviality arguments, vacuum stability, and precision electroweak measurements are discussed. Effective Lagrangian techniques are used to understand potential deviations from the Standard Model (SM) predictions. Finally, I end with a brief discussion of the future of Higgs physics.
This is the introduction to the PhD thesis, defended in June 2006. In the original form it was appended with the reprints of the author's published papers, and is to be regarded as their summary. Full details may be found in the quoted papers.
We study a classically scale-invariant model in which strong dynamics in a dark sector sets the scale of electroweak symmetry breaking. Our model is distinct from others of this type that have appeared in the recent literature. We show that the Higgs sector of the model is phenomenologically viable and that the spectrum of dark sector states includes a partially composite dark matter candidate.
The modern precision accelerator data has essentially ruled out the most obvious model of dynamical electroweak symmetry breaking, technicolour. The idea is though well motivated and it is important to construct models compatible with the precision data of this ilk to motivate experimental searches. We describe the top-see-saw and flavour universal symmetry breaking models that break electroweak symmetry dynamically yet have a decoupling limit for all new physics. Limits on the scale of such new physics may be placed using precision data and direct search results from the Tevatron.
Recent progress in calculating O(alpha) electroweak corrections to W+W- pair production in photon-photon collisions is reviewed. The potential of the Photon Linear Collider to study anomalous W couplings is discussed.
The connection between the scales of $ {\rm SU} (2)\times {\rm U} (1) $ gauge symmetry breaking and supersymmetry breaking is didactically displayed in the framework of a T.O.Y. (Theory Overestimating Yukawas) model, a version of the $ (M+1)SSM $ (supersymmetric extension of the standard model with a gauge singlet) in which the relevant parameters are determined in the fixed point regime. Some conspicuous features of supersymmetric particle physics are reviewed in the light of this simplified model. An alternative theory corresponding to lim $ (M+1)SSM \longrightarrow MSSM, $ leads to interest…
In this talk, I discuss theoretical advances in understanding the properties of the Higgs boson and the implications for models of electroweak symmetry breaking. I begin by reviewing some of the recent progress in Standard Model calculations for Higgs boson production and decay rates, followed by a lightning tour of the use of effective field theories in the search for new physics in the Higgs sector. I end with a discussion of the complementarity of precision Higgs coupling measurements and direct searches for heavy particles for the discovery of Beyond the Standard Model physics in the elect…
