Roshan Foadi, Francesco Sannino
We analyze the WW scattering in scenarios of dynamical electroweak symmetry breaking of walking technicolor type. We show that in these theories there are regions of the parameters space allowed by the electroweak precision data, in which unitarity violation is delayed at tree level up to around 3-4 TeV without the inclusion of any sub-TeV resonances.
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A slowly running technicolor coupling will affect the size of non-oblique corrections to the $Zb\bar b$ vertex from extended technicolor dynamics. We show that while ``walking technicolor'' reduces the magnitude of the corrections, they generally remain large enough to be seen at LEP.
We show how to constrain the physical spectrum of walking technicolor models via precision measurements and modified Weinberg sum rules. We also study models possessing a custodial symmetry for the S parameter at the effective Lagrangian level - custodial technicolor - and argue that these models cannot emerge from walking type dynamics. We suggest that it is possible to have a very light spin-one axial vector boson. However, in the walking dynamics the associated vector boson is heavy while it is degenerate with the axial in custodial technicolor.
We examine the effect of walking technicolor dynamics on the electroweak $S$ parameter and contrast it with the effect of QCD-like technicolor dynamics. Our main tools are the operator product expansion for the high-momentum behavior of the electroweak gauge boson vacuum polarizations and the analyticity of these polarizations which relate their low and high momentum behaviors. We show that whereas in large QCD-like technicolor models $S$ is large and positive, in walking technicolor models a negative contribution is emphasized, related to the large anomalous dimension of the technifermion con…
I report on our construction and analysis of the effective low energy Lagrangian for the Minimal Walking Technicolor (MWT) model. The parameters of the effective Lagrangian are constrained by imposing modified Weinberg sum rules and by imposing a value for the S parameter estimated from the underlying Technicolor theory. The constrained effective Lagrangian allows for an inverted vector vs. axial-vector mass spectrum in a large part of the parameter space.
Based on Refs.1 and 2, we study the couplings of the scalar bound state to the fermions and the weak bosons in walking gauge theories.
We investigate the possibility of a dark matter candidate emerging from a minimal walking technicolor theory. In this case techniquarks as well as technigluons transform under the adjoint representation of SU(2) of technicolor. It is therefore possible to have technicolor neutral bound states between a techniquark and a technigluon. We investigate this scenario by assuming that such a particle can have a Majorana mass and we calculate the relic density. We identify the parameter space where such an object can account for the full dark matter density avoiding constraints imposed by the CDMS and…
Different theoretical and phenomenological aspects of the Minimal and Nonminimal Walking Technicolor theories have recently been studied. The goal here is to make the models ready for collider phenomenology. We do this by constructing the low energy effective theory containing scalars, pseudoscalars, vector mesons and other fields predicted by the minimal walking theory. We construct their self-interactions and interactions with standard model fields. Using the Weinberg sum rules, opportunely modified to take into account the walking behavior of the underlying gauge theory, we find interesting…
We construct the non-linear realized Lagrangian for the Goldstone Bosons associated to the breaking pattern of SU(4) to SO(4). This pattern is expected to occur in any Technicolor extension of the standard model featuring two Dirac fermions transforming according to real representations of the underlying gauge group. We concentrate on the Minimal Walking Technicolor quantum number assignments with respect to the standard model symmetries. We demonstrate that for, any choice of the quantum numbers, consistent with gauge and Witten anomalies the spectrum of the pseudo Goldstone Bosons contains e…
I discuss recent progress in the uncovering of the phase diagram of non-supersymmetric gauge theories. The nature of the conformal window for higher dimensional representations suggests a possible way to construct realistic technicolor models. I then explicitly provide two such theories. One of these models also has a natural cold Dark Matter candidate.
The LHC Higgs can be identified as the technidilaton, a composite scalar, arising as a pseudo Nambu-Goldstone boson for the spontaneous breaking of scale symmetry in walking technicolor. One interesting candidate for the walking technicolor is the QCD with the large number of fermion flavors, involving the one-family model having the eight-fermion flavors. The smallness of the technidilaton mass can be ensured by the generic walking feature, Miransky scaling, and the presence of the "anti-Veneziano limit" characteristic to the large-flavor walking scenario. To tell the standard-model Higgs fro…
Walking technicolor, having a large anomalous dimension $γ_m \simeq 1$ and approximate scale symmetry, predicts Technidilaton, a light composite Higgs as a pseudo-Nambu-Goldstone boson of the approximate scale symmetry, which can be identified with the 125 GeV boson discovered at LHC. I will describe how such a {\it weakly coupled light composite scalar} can be dynamically realized in the {\it strongly coupled dynamics}, and can be fit to the current data at LHC, based on the ladder-like computation and the holographic one. I will also present results of our lattice collaboration (LatKMI Colla…
There are quasi-conformal theories, like the Minimal and Ultraminimal Technicolor models, which may break dynamically the gauge symmetry of the Standard Model and at the same time are compatible with electroweak precision data. The main characteristic of this type of models is their fermionic content in one or more higher dimensional representations, therefore it is not immediate to know which model leads to the most attractive channel or the minimum vacuum energy state. We discuss the effective potential for composite operators for these models, verifying that their vacuum energy values are d…
Dynamical electro-weak symmetry breaking is an appealing, strongly-coupled alternative to the weakly-coupled models based on an elementary scalar field developing a vacuum expectation value. In the first two sections of this set of lectures, I summarize the arguments, based on low-energy phenomenology, supporting walking technicolor as a realistic realization of this idea. This pedagogical introduction to walking technicolor, and more generally to the physics of extensions of the standard model, makes extensive use of effective field theory arguments, symmetries and counting rules. The strongl…
We calculate the one-loop $Z^0$-penguin contributions to the rare K-decays, $K^+ \to π^+ ν\bar ν$, $K_L \to π^0 ν\bar ν$ and $K_L \to μ^+ μ^-$, from the unit-charged technipions $π_1$ and $π_8$ in the framework of the Multiscale Walking Technicolor Model. We find that: (a) the $π_1$ and $π_8$ can provide one to two orders enhancements to the branching ratios of the rare K-decays; (b) by comparing the experimental data of $Br(K^+ \to π^+ ν\bar ν)$ with the theoretical prediction one finds the lower mass bounds, $m_{p8} \geq 249 GeV$ for $F_Q=40GeV$ and $m_{p1}=100 GeV$; (c) by comparing the exp…
Applying the perturbative QCD ( PQCD ) method, we study the decay $B_c\rightarrow D_s^*γ$ in the standard model and multiscale walking technicolor model. In the SM, we find that the contribution of weak annihilation is more important than that of the electromagnetic penguin. The presence of Pseudo-Goldstone-Bosons in the MWTCM leads to a large enhancement in the rate of $B_c\rightarrow D_s^*γ$, but this model is in conflict with the branching ratio of $Z\rightarrow b\overline b$ ( $R_b$ ) and the CLEO data on the branching ratio BR ( $b\rightarrow sγ$ ). If topcolor is further introduced, the …
We interpret the recent data on non-observation of Z'- and W'-bosons, reported by CMS, within Minimal Walking Technicolor models and use them to constrain the couplings and spectrum of the theory. We provide the reach for both exclusion and possible observation for the LHC with 5 fb^-1 at 7 TeV in the centre of mass energy, and 100 fb^-1 at 13 TeV.
We investigate the potential of the Large Hadron Collider (LHC) to probe one of the most compelling Beyond the Standard Model (BSM) frameworks --- Walking Technicolor (WTC), involving strong dynamics and having a slowly running (walking) new strong coupling. For this purpose we use recent LHC Run2 data to explore the full parameter space of the minimal WTC model using dilepton signatures from heavy neutral $Z^{\prime}$ and $Z^{\prime\prime}$ resonances predicted by the model. This signature is the most promising one for discovery of WTC at the LHC for the low-intermediate values of the $\tilde…
We calculate masses of the technipions in the walking technicolor model with the anomalous dimension gamma_m =1, based on a holographic model which has a naturally light technidilaton phi as a composite Higgs with mass m_phi simeq 125 GeV. The one-family model (with 4 weak-doublets) is taken as a concrete example in such a framework, with the inputs being F_pi=v/2 simeq 123 GeV and m_phi simeq 125 GeV as well as gamma_m=1. It is shown that technipion masses are enhanced by the large anomalous dimension to typically O(1) TeV. We find a correlation between the technipion masses and S^{(TC)}, the…
A realistic technicolor model is presented with the dynamics below $150$ TeV treated explicitly. Electroweak symmetry is broken by the condensates of a `minimal' doublet of technifermions. The new feature of the model is that the the third generation quarks are unified with the technifermions into multiplets of a walking gauge force down to a scale of $10$ TeV. The remaining quarks and leptons are not involved in this unification however. The walking dynamics enhances the higher dimension interactions which give the ordinary fermions their masses and mixing, while leaving flavor-changing neutr…
We calculate the contributions to the rare B-decays, $B \to X_{s,d} ν\bar ν$, $B_{s,d} \to l^+l^- $ from the unit-charged technipions. Within the considered parameter space we find that: (a) the enhancements to the branching ratios in question can be as large as three orders of magnitude; (b) the ALEPH data of $B \to X_s ν\bar ν$ lead to strong mass bounds on $m_{p1}$ and $m_{p8}$: $m_{p8} \geq 620, 475 GeV$ for $F_Q=40GeV$ and $m_{p1}=100, 400 GeV$ respectively. (c) the CDF data of $B_s \to μ\bar μ$ lead to a relatively weak limit: $m_{p8} \geq 320 GeV$ for $F_Q=40GeV$ and $m_{p1}=200 GeV$.
We investigate the structure and the novel emerging features of the mesonic non-singlet spectrum of the Minimal Walking Technicolor (MWT) theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which MWT is (almost) conformal in the infrared, while spontaneous chiral symmetry breaking seems less plausible.
We present a Monte Carlo renormalisation group study of the SU(2) gauge theory with two Dirac fermions in the adjoint representation. Using the two lattice matching technique recently advocated and exploited in [arXiv:0907.0919], we measure the running of the coupling and the anomalous mass dimension.
We study a superweakly interacting dark matter particle motivated by minimal walking technicolor theories. Our WIMP is a mixture of a sterile state and a state with the charges of a standard model fourth family neutrino. We show that the model can give the right amount of dark matter over a range of the WIMP mass and mixing angle. We compute bounds on the model parameters from the current accelerator data including the oblique corrections to the precision electroweak parameters, as well as from cryogenic experiments, Super-Kamiokande and from the IceCube experiment. We show that consistent dar…
We map the phase diagram of gauge theories of fundamental interactions in the flavor-temperature plane using chiral perturbation theory to estimate the relation between the pion decaying constant and the critical temperature above which chiral symmetry is restored. We then investigate the impact of our results on models of dynamical electroweak symmetry breaking and therefore on the electroweak early universe phase transition.
In these lectures we present the motivation for dynamical electroweak symmetry breaking and its most popular realization, technicolor. We introduce the basic ideas of technicolor and its companion theory of flavor, extended technicolor. We review the classical theory of technicolor, based on naive scaling from quantum chromodynamics, and discuss the classical theory's fatal flaws. Finally, we describe the principal attempt to correct these flaws, the theory of walking technicolor.
It is quite possible that the Technicolor problems are related to the poorly known self-energy expression, or the way chiral symmetry breaking (CSB) is realized in non-abelian gauge theories. Actually, the only known laboratory to test the CSB mechanism is QCD. The TC dynamics may be quite different from the QCD , this fact has led to the walking TC proposal making the new strong interaction almost conformal and changing appreciably its dynamical behavior. There are different ways to obtain of extreme walking (or quasi-conformal) technicolor theories, in this paper we propose an scheme to obta…
I describe a technicolor model (without walking) of all interactions up to energies of the order of 1000~TeV. The low energy extended technicolor model has the CTSM form. But at intermediate energy scales, additional interactions are required to give the KM mixing. I discuss the characteristic flavor changing neutral current interactions arising from this flavor physics below 1000~TeV.
Precision electroweak measurements have been claimed to eliminate almost all models of technicolor. We show that the assumptions made to calculate the oblique parameters $S$,$T$,$U$ apply to QCD--like technicolor models which were ruled out long ago on much firmer grounds. These assumptions are invalid in modern ``walking'' technicolor models.
We explicitly calculate the $S$ parameter in entire parameter space of the holographic walking/conformal technicolor (W/C TC), based on the deformation of the holographic QCD by varying the anomalous dimension from $γ_m \simeq 0$ through $γ_m \simeq 1$ continuously. The $S$ parameter is given as a positive monotonic function of $ξ$ which is fairly insensitive to $γ_m$ and continuously vanishes as $S \sim ξ^2 \to 0$ when $ξ\to 0$, where $ξ$ is the vacuum expectation value of the bulk scalar field at the infrared boundary of the 5th dimension $z=z_m$ and is related to the mass of (techni-) $ρ$ m…
In this lecture I give an introduction to technicolor and extended technicolor theories. I discuss the issues models of dynamical electroweak symmetry breaking struggle with and propose how non QCD-like dynamics, such as a `walking' or nearly-conformal technicolor coupling, can invalidate many conventional arguments against technicolor. I provide a short discussion of AdS/CFT-inspired extra-dimensional (Higgsless) models and their similarities and differences with older 4D technicolor models. To conclude, a summary of some possible LHC signatures is given.
We present a Monte Carlo renormalisation group study of the SU(2) gauge theory with two Dirac fermions in the adjoint representation. Using the two-lattice matching technique we measure the running of the coupling and the anomalous mass dimension. We find slow running of the coupling, compatible with an infrared fixed point. Assuming this running is negligible we find a vanishing anomalous dimension, gamma=-0.03(13), however taking this source of systematic error into account gives a much larger range of allowed values, -0.6 < gamma < 0.6. We also attempt to measure the anomalous mass dimensio…
We perform a lattice study of the topological susceptibility and instanton size distribution of the $\su{2}$ gauge theory with two adjoint Dirac fermions (also known as Minimal Walking Technicolor), which is known to be in the conformal window. In the theory deformed with a small mass term, by drawing a comparison with the pure gauge theory, we find that topological observables are decoupled from the fermion dynamics. This provides further evidence for the infrared conformality of the theory. A study of the instanton size distribution shows that this quantity can be used to detect the onset of…
Assuming that the observed Higgs-like resonance at the Large Hadron Collider is a technicolor isosinglet scalar (the technicolor Higgs), we argue that the standard model top-induced radiative corrections reduce its dynamical mass towards the desired experimental value. We then discuss conditions for the spectrum of technicolor theories to feature a technicolor Higgs with the phenomenologically required dynamical mass. We use scaling laws coming from modifying the technicolor matter representation, number of technicolors, techniflavors as well as the number of doublets gauged under the electrow…
We compute an effective action for a composite Higgs boson formed by new fermions belonging to a general technicolor non-Abelian gauge theory, using a quite general expression for the fermionic self-energy that depends on a certain parameter (alpha), that defines the technicolor theory from the extreme walking behavior up to the one with a standard operator product expansion behavior. We discuss the values of the trilinear and quadrilinear scalar couplings. Our calculation spans all the possible physical possibilities for mass and couplings of the composite system. In the case of extreme walki…
Several phenomenologically viable walking technicolor models have been proposed recently. I demonstrate that these models can have first order electroweak phase transitions, which are sufficiently strong for electroweak baryogenesis. Strong dynamics can also lead to several separate transitions at the electroweak scale, with the possibility of a temporary restoration and an extra breaking of the electroweak symmetry. First order phase transitions will produce gravitational waves, which may be detectable at future experiments.
Walking technicolor (WTC) models predict the existence of heavy neutral pseudo-Goldstone bosons (PGBs), whose masses are typically expected to be larger than 100 GeV. In this paper, we investigate the production and decay of these particles at the high energy e^+ e^- experiments, LEP II and NLC. We find that, in WTC models, the production of neutral PGBs can be significantly enhanced, by one or two orders of magnitude, with respect to the predictions of traditional (QCD-like) TC models. The origin of such an enhancement is the existence of several low energy TC scales, that are likely to appea…
We propose a new dark matter candidate, {\it light decoupled techni-dilaton}, which arises from the almost scale-invariant/conformal (walking) technicolor. We investigate its characteristic nature and discuss several cosmological and astrophysical constraints. It turns out that techni-dilatons are extremely weakly interacting and produced dominantly by the non-thermal mechanism to be the main component of dark matter with mass range between around 0.01 eV and 500 eV for typical walking technicolor scenarios.
We investigate the strongly coupled minimal walking technicolor model (MWT) in the framework of a bottom-up holographic model, where the global $SU(4)$ symmetry breaks to $SO(4)$ subgroup. In the holographic model, we found that 125GeV composite Higgs particles and small Peskin-Takeuchi $S$ parameter can be achieved simultaneously. In addition, the model predicts a large number of particles at the TeV scale, including dark matter candidate Technicolor Interacting Massive Particles (TIMPs). If we consider the dark matter nuclear spin-independent cross-section in the range of $10^{-45}\sim 10 ^ …
We study gravitational waves from the first-order electroweak phase transition in the $SU(N_c)$ gauge theory with $N_f/N_c\gg 1$ ("large $N_f$ QCD") as a candidate for the walking technicolor, which is modeled by the $U(N_f)\times U(N_f)$ linear sigma model with classical scale symmetry (without mass term), particularly for $N_f=8$ ("one-family model"). This model exhibits spontaneous breaking of the scale symmetry as well as the $U(N_f)\times U(N_f)$ radiatively through the Coleman-Weinberg mechanism $\grave{a}$ la Gildener-Weinberg, thus giving rise to a light pseudo dilaton (techni-dilaton)…
We give an introduction to the dynamical symmetry breaking with large anomalous dimension. This is the basis of tightly bound composite Higgs models such as walking technicolor, strong ETC technicolor and top quark condensate, which are all characterized by the large anomalous dimension, γ_m \simeq 1 (walking technicolor), 1<γ_m<2 (strong ETC technicolor) and γ_m \simeq 2 (top quark condensate) due to nontrivial short distance dynamics of the gauged Nambu-Jona-Lasinio (NJL) models (gauge theories plus four-fermion interactions). Particular emphasis will be placed on the top quark condensate in…
The ATLAS collaboration has recently reported an excess of about 2.5 $σ$ global significance at around 2 TeV in the diboson channel with the boson-tagged fat dijets, which may imply a new resonance beyond the standard model. We provide a possible explanation of the excess as the isospin-triplet technivector mesons (technirhos, denoted as $ρ_Π^{\pm,3}$) of the walking technicolor in the case of the one-family model as a benchmark. As the effective theory for the walking technicolor at the scales relevant to the LHC experiment, we take a scale-invariant version of the hidden local symmetry model…
Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the …
We investigate the effects of four-fermion interactions on the phase diagram of strongly interacting theories for any representation as function of the number of colors and flavors. We show that the conformal window, for any representation, shrinks with respect to the case in which the four-fermion interactions are neglected. The anomalous dimension of the mass increases beyond the unity value at the lower boundary of the new conformal window. We plot the new phase diagram which can be used, together with the information about the anomalous dimension, to propose ideal models of walking technic…
We discuss the selection of fermion representations in technicolor models with a view toward minimizing technicolor contributions to the precision electroweak $S$ parameter. We present and analyze models that involve one technifermion SU(2)$_L$ doublet with standard-model singlet technifermion sectors that lead to walking behavior, which further reduces $S$. We also consider models that have technifermions in higher-dimensional representations and study embeddings in extended technicolor theories.
We study the gauge sector of Minimal Walking Technicolor, which is an SU(2) gauge theory with nf=2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices Nt x Ns^3, with Ns ranging from 8 to 16 and Nt=2Ns, at fixed β=2.25, and varying the fermion bare mass m0, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to the conclusion that the infrared dynamics is gi…
We use a holographic description of technicolor dynamics to study gauge theories that only break chiral symmetry when aided by a strong four fermion interaction. These Nambu-Jona-Lasinio (NJL) assisted technicolor models provide examples of different dynamics from walking technicolor which can, by tuning, generate a light higgs like $σ$ meson. We compute the vector meson ($ρ$) and axial vector meson (A) spectrum for a variety of models with techni-quarks in the fundamental representation, enlarging the available parameter space over a previous analysis of walking theories. These predictions de…
We propose an approach for the calculation of the yukawa coupling through the scalar decay constant and the chiral condensate in the context of the extended technicolor (ETC). We perform the nonperturbative computation of the yukawa coupling based on the improved ladder Schwinger-Dyson equation. It turns out that the yukawa coupling can be larger or smaller than the standard model (SM) value, depending on the number $N_D$ of the weak doublets for each technicolor (TC) index. It is thus nontrivial whether or not the huge enhancement of the production of the scalar via the gluon fusion takes pla…
We unveil the temperature-dependent electroweak phase transition in new extensions of the Standard Model in which the electroweak symmetry is spontaneously broken via strongly coupled, nearly-conformal dynamics achieved by the means of multiple matter representations. In particular, we focus on the low energy effective theory introduced to describe Ultra Minimal Walking Technicolor at the phase transition. Using the one-loop effective potential with ring improvement, we identify regions of parameter space which yield a strong first order transition. A striking feature of the model is the exist…
We summarize basic features associated to dynamical breaking of the electroweak symmetry. The knowledge of the phase diagram of strongly coupled theories as function of the number of colors, flavors and matter representation plays a fundamental role when trying to construct viable extensions of the standard model (SM). Therefore we will report on the status of the phase diagram for SU(N) gauge theories with fermionic matter transforming according to arbitrary representations of the underlying gauge group. We will discuss how the phase diagram can be used to construct unparticle models. We will…
A fifth force, of technicolor type, responsible for breaking the electroweak theory is an intriguing extension of the Standard Model. Recently new theories have been shown to feature walking dynamics for a very low number of techniflavors and are not ruled out by electroweak precision measurements. We identify the light degrees of freedom and construct the associated low energy effective theories. These can be used to study signatures and relevant processes in current and future experiments. In our theory the technibaryons are pseudo Goldstone bosons and their masses arise via extended technic…
These two lectures on technicolor and extended technicolor (ETC) were presented at l'Ecole de GIF at LAPP, Annecy-le-Vieux, France, in September 2001. In Lecture I, the motivation and structure of this theory of dynamical breaking of electroweak and flavor symmetries is summarized. The main phenomenological obstacles to this picture--flavor-changing neutral currents, precision electroweak measurements, and the large top-quark mass--are reviewed. Then, their proposed resolutions--walking technicolor and topcolor-assisted technicolor are discussed. In Lecture II, a scenario for CP violation is p…
Slowly walking technicolor models provide a mechanism for electroweak symmetry breaking whose nonperturbative lattice investigation is rather challenging. Here we demonstrate walking near a conformal fixed point considering the 2-d lattice O(3) model at vacuum angle $θ\approx π$. The essential features of walking technicolor models are shared by this toy model and can be accurately investigated by numerical simulations. We show results for the running coupling and the beta-function and we perform a finite size scaling analysis of the massgap close to the conformal point.
A new particle at around 125 GeV has been observed at the LHC, which we show could be identified with the techni-dilaton (TD) predicted in the walking technicolor and thus should be an evidence of walking technicolor. The TD is a pseudo Nambu-Goldstone boson for the approximate scale symmetry spontaneously broken by techni-fermion condensation, with its lightness being ensured by the approximate scale invariance of the walking technicolor. We test the goodness-of-fit of the TD signatures using the presently available LHC data set, and show that the 125 GeV TD is actually favored by the current…
If the 750 GeV diphoton excess is identified with the color-singlet isosinglet-technipion, $P^0$ (750), in the one-family walking technicolor, as in our previous paper, then there should exist another color-singlet technipion, isotriplet one, $P^{\pm,3}$, definitely predicted at around 950 GeV independently of the dynamical details. The $P^{\pm,3}(950)$ are produced at the LHC via vector boson and photon fusion processes, predominantly decaying to $W γ$, and $γγ$, respectively. Those walking technicolor signals can be explored at the Run 2, or 3, which would further open a way to a plethora of…
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.
We consider the possibility to continue the $Z_6$ symmetry of the Standard Model to the Technicolor theories. Among the SU(N) Weinberg - Susskind models and the SU(N) Farhi - Susskind models for $N>2$ only the SU(4) Farhi - Susskind model may possess the mentioned symmetry. We also show that the hypercharge assignment of Minimal Walking SU(2) Technicolor model may be chosen in such a way that the additional discrete symmetry is preserved.
We investigate the production and possible detection of gravitational waves stemming from the electroweak phase transition in the early universe in models of minimal walking technicolor. In particular we discuss the two possible scenarios in which one has only one electroweak phase transition and the case in which the technicolor dynamics allows for multiple phase transitions.
Technicolor achieves electroweak symmetry breaking (EWSB) in an elegant and natural way, while it suffers from severe model building difficulties. I propose to abandon its secondary goal to eliminate scalar bosons in exchange of solving numerous problems using supersymmetry. It helps to understand walking dynamics much better with certain exact results. In the particular model presented here, there is no light elementary Higgs boson and the EWSB is fully dynamical, hence explaining the hierarchy; There is no alignment problem and no light pseudo-Nambu-Goldstone bosons exist; The fermion masses…
We study the oblique corrections to the electroweak interaction in the holographic model of technicolor theories. The oblique S parameter is expressed in terms of a solution to the equations of motion for the AdS bulk gauge fields. By analyzing the solution, we establish a rigorous proof that the S parameter is positive and is reduced by walking. We also present the precise numerical values for the S parameter of various technicolor models by solving the equations numerically.
We analyze the potential of the Large Hadron Collider (LHC) to observe signatures of phenomenologically viable Walking Technicolor models. We study and compare the Drell-Yan (DY) and Vector Boson Fusion (VBF) mechanisms for the production of composite heavy vectors. We find that the heavy vectors are most easily produced and detected via the DY processes. The composite Higgs phenomenology is also studied. If Technicolor walks at the LHC its footprints will be visible and our analysis will help uncovering them.
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