Top Condensate Model Research Articles

Top condensation model: a step towards the correct prediction of the Higgs mass

A realization of the composite Higgs scenario in the context of the effective model with the SU(2)_Ltimes U(1)_R symmetric four-Fermi interactions proposed by Miransky, Tanabashi and Yamawaki is studied. The model implements Nambu’s mechanism of dynamical electroweak symmetry breaking leading to the formation of {{bar{t}}}t and {{bar{b}}}b quark condensates. We explore the vacuum structure and spectrum of the model by using the Schwinger proper-time method. As a direct consequence of this mechanism, the Higgs acquires a mass in accord with its experimental value. The present prediction essentially differs from the known overestimated value, m_chi = 2m_t, making more favourable the top condensation scenario presented here. The mass formulas for the members of the second Higgs doublet are also obtained. The Nambu sum rule is discussed. It is shown that the anomalous U(1)_A symmetry breaking modifies this rule at next to leading order in 1/N_c.

Catalysis of the 〈b̄b〉 Condensate in the Composite Higgs Model

The problem of appearance of quark masses through the mechanism of dynamical breaking of the SU(2)L × U(1)R symmetry of electroweak interactions has been studied within a model with local four-quark interactions, which result in the formation of a 〈tt〉 condensate and composite Higgs bosons. We show that this process catalyzes bb condensation in the presence of an arbitrarily weak’ t Hooft interaction. The spectrum of composite scalar excitations has been calculated. An expression obtained for the mass of a standard Higgs boson significantly improves the agreement of the top-condensation model with the experiment. It has been shown that the standard Higgs boson under the Nambu sum rules should have three partners with the same mass of about 245 GeV and different electric charges. The possibility of a transition of the system to a chiral symmetric phase, which is accompanied by the corresponding change in the spectrum of elementary excitations, is discussed.

Dynamical symmetry breaking and negative cosmological constant

In the context of Clifford functional integral formalism, we revisit the Nambu–Jona-Lasinio-type dynamical symmetry breaking model and examine the properties of the dynamically generated composite bosons. Given that the model with 4-fermion interactions is nonrenormalizable in the traditional sense, the aim is to gain insight into the divergent integrals without resorting to explicit regularization. We impose a restriction on the linearly divergent primitive integrals, thus resolving the long-standing issue of momentum routing ambiguity associated with fermion–antifermion condensations. The removal of the ambiguity paves the way for the possible calculation of the true ratio of Higgs boson mass to top quark mass in the top condensation model. In this paper, we also investigate the negative vacuum energy resulted from dynamical symmetry breaking and its cosmological implications. In the framework of modified Einstein–Cartan gravity, it is demonstrated that the late-time acceleration is driven by a novel way of embedding the Hubble parameter into the Friedmann equation via an interpolation function, whereas the dynamically generated negative cosmological constant only plays a minor role for the current epoch. Two cosmic scenarios are proposed, with one of which suggesting that the universe may have been evolving from an everlasting coasting state towards the accelerating era characterized by the deceleration parameter approaching −0.5 at low redshift. One inevitable outcome of the modified Friedmannian cosmology is that the directly measured local Hubble parameter should in general be larger than the Hubble parameter calibrated from the conventional Friedmann equation. This Hubble tension becomes more pronounced when the Hubble parameter is comparable or less than a characteristic Hubble scale.

Top-Mode pseudo-Nambu–Goldstone Boson Higgs model

We discuss the Top-Mode pseudo-Nambu–Goldstone Boson Higgs (TMpNGBH) model which has recently been proposed as a variant of the top quark condensate model in light of the 125 GeV Higgs boson discovered at the LHC. In this talk, we focus on the vacuum alignment and the phenomenologies of characteristic particles of the TMpNGBH model.

Holograms of a dynamical top quark

We present holographic descriptions of dynamical electroweak symmetry breaking models that incorporate the top mass generation mechanism. The models allow computation of the spectrum in the presence of large anomalous dimensions due to walking and strong Nambu--Jona-Lasinio interactions. Technicolor and QCD dynamics are described by the bottom-up Dynamic AdS/QCD model for arbitrary gauge groups and numbers of quark flavors. An assumption about the running of the anomalous dimension of the quark bilinear operator is input, and the model then predicts the spectrum and decay constants for the mesons. We add Nambu--Jona-Lasinio interactions responsible for flavor physics from extended technicolor, top-color, etc., using Witten's multitrace prescription. We show the key behaviors of a top condensation model can be reproduced. We study generation of the top mass in (walking) one doublet and one family technicolor models and with strong extended technicolor interactions. The models clearly reveal the tensions between the large top mass and precision data for $\ensuremath{\delta}\ensuremath{\rho}$. The necessary tunings needed to generate a model compatible with precision constraints are simply demonstrated.

A composite Higgs model with minimal fine-tuning: The large-Nand weak-technicolor limit

We suggest a criterion to minimize the amount of fine-tuning in a composite Higgs model. The paradigm of this type of model is the top-condensate model of Bardeen, Hill and Lindner (BHL). Although "minimally fine-tuned", this model failed to account correctly for the masses of the top quark and the 125~GeV Higgs boson. We propose a generalization of the BHL model that employs finely-tuned extended technicolor (ETC) plus technicolor (TC) interactions. The additional freedom of this model may accommodate both m_t(173) and M_H(125). This paper studies the large-N_{TC} and N_C limit of this model in which technicolor is weak and does not contribute to electroweak symmetry breaking. Refinements including walking-TC dynamics and a renormalization group analysis of m_t and M_H will appear in a subsequent paper. A likely generic signal of this model is enhanced production of dibosons (W^+W^- and W^\pm Z^0) and tribosons (W^+W^- Z^0) via rho_T^{0,\pm} and omega_T decay.

Tree level relations in a composite electroweak theory

We work out simple tree level relations in a top condensate model with dynamical electroweak symmetry breaking. We find that in this picture the mass of the composite Higgs boson at tree level is given by [Formula: see text] where mt is the mass of the top quark.

A hierarchy of the quark masses in a top condensate model with multiple Higgses

We discuss the quark masses in a top condensate model where not only two quark but also four quark composite states may exist. We show that the presence of the top color group SU (3)1× SU (3)2 with the correct quark representations can justify even in the absence of the additional technicolor interactions a hierarchy of the quark masses where the light quarks masses have the same size, the charm and bottom masses are higher and similar and the top is the heaviest.

Top condensate model with a Higgs doublet and a Higgs triplet

We reconsider top condensate models from the perspective that not only two-quark composite states can form but also four-quark ones. We obtain a model which contains a Higgs doublet and a Higgs triplet, where one of the neutral components of the Higgs triplet identifies with the Higgs boson found at the LHC. We discuss some of the phenomenological consequences.

B-decay signatures of warped top-condensation

We point out that the light radion ϕ in a recently proposed Warped Top-Condensation Model (WTCM), can provide distinct signatures in b→sϕ, where the on-shell ϕ can decay with displaced vertices. We find that some of the parameter space of these models is constrained by B-meson and astrophysical data. Future B-decay measurements can lead to the discovery of the WTCM.

SpontaneousCPsymmetry breaking at the electroweak scale

We present a top-condensation model in which the $CP$ symmetry is spontaneously broken at the electroweak scale due to the condensation of two composite Higgs doublets. In particular the $CP$-violating phase of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix is generated. A simpler model where only one quark family is included is also discussed. In this case, for a general four-fermion interaction (${G}_{tb}\ensuremath{\ne}0$), the particle spectrum is the one of the one Higgs doublet model.

HIGGS MASS IN THE STANDARD MODEL FROM COUPLING CONSTANT REDUCTION

Plausible interrelations between parameters of the standard model are studied. The empirical value of the top quark mass, when used in the renormalization group equations, suggests that the ratio of the color SU(3) gauge coupling g3, and the top coupling gt is independent of the renormalization scale. On the other hand, the variety of top-condensate models suggests that the Higgs self-coupling λ is proportional to [Formula: see text]. Invoking the requirement that the ratio [Formula: see text] is independent of the renormalization scale t, fixes the Higgs mass. The pole mass of the Higgs (which differs from the renormalization group mass by a few percent) is found to be ~ 154 GeV for the one-loop equations and ~ 148 GeV for the two-loop equations.

Top-quark mass in the minimal top-condensation model with extra dimensions

The minimal model of dynamical electroweak-symmetry breaking through top condensation in the presence of compact large extra dimensions is studied. It is shown that, owing to the power-law evolution of gauge and Yukawa couplings, the original predictions of Bardeen, Hill, and Lindner for the top-quark mass are significantly lowered and that, even for a small cutoff scale Λ of a few TeV, one can obtain experimentally allowed values.

BOOTSTRAP OF THE SCALAR SECTOR IN TOP–ANTITOP SCATTERING AMPLITUDE

Based on the top-condensate model of Nambu and Bardeen et al., it is pointed out that a bootstrap of the scalar sector occurs in top–antitop scattering amplitude in that the ladder sum of Higgs pole exchange diagrams in one channel reproduces a Higgs pole in the crossed-channel. This result is exact whenever color flows simultaneously in both channel directions e.g. for Nc = 1. Solutions are obtained that are compatible with the condensate models such as the top-color models which imply large top-Yukawa couplings at the top mass.

Scalars from Top-Condensation Models at Hadron Colliders

We study the production and decay of neutral scalars and pseudo-scalars at hadron colliders, in theories where the top-quark mass is the result of a $t\bar t$ condensate. We show that the dominant decay channel for masses below the $t\bar t$ threshold is the flavor changing mode $tc$. This is a consequence of the non-universal nature of the underlying interactions in all top-condensation models and provides a model-independent signature of these scenarios. We show that an upgraded Tevatron is sensitive to a sizeable region of the interesting parameter space and that the LHC will highly constrain these models through this flavor violating channel.

Composite photon and W±, Z0 vector bosons from a top-condensation model at fixed v=247 GeV

Starting from the historical Fermi four-fermion low-energy effective electroweak interactions Lagrangian for the third generation of quarks, augmented by an NJL type interaction responsible for dynamical symmetry breaking and heavy quark mass generation, and fixing the scalar (Higgs) field v.e.v. at v = 247 GeV, we show that: (1) heavy quark bound states Q Q ̄ with quantum numbers of the W ± bosons exist for arbitrarily weak (positive) vector coupling G F , so long as the quark mass is sufficiently large; (2) a massive composite neutral vector boson ( Z 0) appears; (3) a massless composite parity-conserving neutral vector boson ( γ) appears, the composite Higgs-Kibble ghosts decouple from the quarks and other particles, the longitudinal components of the vector boson propagators vanish, as G F→G F expt. =1/( 2 v 2) , which also implies that the cutoff Λ→∞. Thus, the Fermi interaction model is equivalent to a locally gauge invariant theory but with definite values of coupling constants and masses. The model discussed here was chosen for illustrative purposes and is not equivalent to the Standard Model.

Flavor universal dynamical electroweak symmetry breaking

The top condensate see-saw mechanism of Dobrescu and Hill allows electroweak symmetry to be broken while deferring the problem of flavour to an electroweak singlet, massive sector. We provide an extended version of the singlet sector that naturally accommodates realistic masses for all the standard model fermions, which play an equal role in breaking electroweak symmetry. The models result in a relatively light composite Higgs sector with masses typically in the range of (400-700)~GeV. In more complete models the dynamics will presumably be driven by a broken gauged family or flavour symmetry group. As an example of the higher scale dynamics a fully dynamical model of the quark sector with a GIM mechanism is presented, based on an earlier top condensation model of King using broken family gauge symmetry interactions (that model was itself based on a technicolour model of Georgi). The crucial extra ingredient is a reinterpretation of the condensates that form when several gauge groups become strong close to the same scale. A related technicolour model of Randall which naturally includes the leptons too may also be adapted to this scenario. We discuss the low energy constraints on the massive gauge bosons and scalars of these models as well as their phenomenology at the TeV scale.

Top-quark condensation

Top quark condensation, in particular the minimal framework where the neutral Higgs scalar is (predominantly) an effective ¯ tt condensate of the stan- dard model, is reviewed. Computational approaches are compared and sim- ilarities, differences and deficiencies pointed out. Extensions of the minimal framework, including scenarios with two composite Higgs doublets, additional neutrino condensates, andcondensation arising from four-fermion interac- tions with enlarged symmetries, are described. Possible renormalizable mod- els of underlying physics potentially responsible for the condensation, includ- ing topcolor assisted technicolor frameworks, are discussed. Phenomenological implications of top condensate models are outlined. Outstanding theoretical issues and problems for future investigation are pointed out. Progress in the field after this article was accepted has been briefly covered in a Note added at the end.

A Modification of the Compositeness Condition in Top-Condensation Models and Vacuum Stability

A Modification of the Compositeness Condition in Top-Condensation Models and Vacuum Stability

Higher dimensional operators in top quark condensation from a renormalization group point of view

The predictive power of top-condensation models strongly depends on the behaviour of higher dimensional operators. These are analyzed in this paper by an extension of the standard renormalization group (RG) arguments which turns out to be a surprisingly powerful tool. Top-condensation models intermediated by underlying scalar exchange can be shown to be mere reparametrizations of the standard model. Further on, RG-arguments show that dynamical vector states cannot be lowered in top-condensation models. Finally we give a general argument concerning the size of higher dimensional operators of heavy vector exchange.