We propose a scenario in which the Planck scale is dynamically linked to the electroweak scale induced by top condensation. The standard model field content, without the Higgs, is promoted to a 5D warped background. There is also an additional 5D fermion with the quantum numbers of the right-handed top. Localization of the zero-modes leads, at low energies, to a Nambu-Jona-Lasinio model that also stabilizes the radion field dynamically thus explaining the hierarchy between the Planck scale and v_EW = 174 GeV. The top mass arises dynamically from the electroweak breaking condensate. The other standard model fermion masses arise naturally from higher-dimension operators, and the fermion mass hierarchies and flavor structure can be explained from the localization of the zero-modes in the extra dimension. If any other contributions to the radion potential except those directly related with electroweak symmetry breaking are engineered to be suppressed, the KK scale is predicted to be about two orders of magnitude above the electroweak scale rendering the model easily consistent with electroweak precision data. The model predicts a heavy (composite) Higgs with a mass of about 500 GeV and standard-model-like properties, and a vector-like quark with non-negligible mixing with the top quark and mass in the 1.6 - 2.9 TeV range. Both can be within the reach of the LHC. It also predicts a radion with a mass of a few GeV that is very weakly coupled to standard model matter.
We discuss the emergence of an inflationary phase in supergravity with the super-Higgs effect due to dynamical spontaneous breaking of supersymmetry, in which the role of the inflaton is played by the gravitino condensate. Realistic models compatible with the Planck satellite CMB data are found in conformal supergravity scenarios with dynamical gravitino masses that are small compared to the Planck mass, as could be induced by a non-trivial vacuum expectation value of the dilaton superfield of appropriate magnitude.
The minimal dynamical electroweak symmetry breaking through top condensation in the presence of compact large extra dimensions is studed. It is shown that thanks to the power-low evolution of gauge and Yukawa couplings the original BHL predictions for the top quark mass are significantly lowered and even for small cut-off scale $Λ\sim few$ TeV one can obtain experimentally allowed values.
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 he…
We point out that the light radion phi in a recently proposed Warped Top-Condensation Model, can provide distinct signatures in b -> s phi, where the on-shell phi 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.
We discuss how the full dynamics of top condensation models can modify the relations between the physical top mass, the amount of custodial $SU(2)$ violation and the weak gauge boson masses. It is emphasized that it is possible to get phenomenologically acceptable relations between $Δρ$, $m_t$ and $M_W$ and that in addition the scale of new physics can be chosen to be ${\cal O}(TeV)$ such that a fine--tuning problem is avoided.
We study the possibility that supersymmetry is broken via a gaugino condensate in four dimensional string theories. We derive an effective low-energy theory describing the Goldstone mode associated with the R-symmetry breaking driven by gaugino condensation and show that this gives a description of gaugino condensation equivalent, at tree level, to other effective Lagrangian approaches based on the symmetries of the theory. A study of the mass gap equation shows that non-perturbative effects favour the appearance of a gaugino condensate. By minimizing the effective potential describing both th…
Top quark condensation, in particular the minimal framework where the neutral Higgs scalar is (predominantly) an effective ${\bar t} t$ condensate of the Standard Model, is reviewed. Computational approaches are compared and similarities, differences and deficiencies pointed out. Extensions of the minimal framework, including scenarios with two composite Higgs doublets, additional neutrino condensates, and ${\bar t}t$ condensation arising from four-fermion interactions with enlarged symmetries, are described. Possible renormalizable models of underlying physics potentially responsible for the …
A recently proposed warped top-condensation model generally predicts a light radion ϕ, with a mass of a few GeV or less, whose interactions are suppressed by a scale of order 100 TeV. In this talk, we present existing constraints and potential signals from the process b \to s ϕ, in the context of such a model. Astrophysical bounds, applicable to very light radions, are also briefly discussed.
In this thesis we study top-condensation models of electroweak symmetry breaking. In particular we investigate a scenario in which the CP symmetry is broken spontaneously due to the same condensates responsible of electroweak symmetry breaking. In this way a CP violating CKM matrix, gauge boson masses, and quark masses are dynamically generated. We started with a new four-fermion interaction such that it can be rewritten using two auxiliary fields. These fields become dynamical and play a similar role as the Higgs field in the SM but being now composite.
Quadratic divergencies which lead to the usual fine-tuning or hierarchy problem are discussed in top condensation models. As in the Standard Model a cancellation of quadratic divergencies is not possible without the boson contributions in the radiative corrections which are absent in lowest order of an $1/N_c$-expansion. To deal with the cancellation of quadratic divergencies we propose therefore an expansion in the flavor degrees of freedom. In leading order we find the remarkable result that quadratic divergencies automatically disappear.
Based on the weak coupling expansion of gravity, we calculate the gravitational contributions to yukawa coupling, scalar quartic coupling as well as gauge couplings with general Landau-DeWitt gauge-fixing choice and a gauge preserving (of SM gauge group) cut off regularization scheme. We find that the results depend on the Landau-DeWitt gauge-fixing parameter. Based on the two loop RGE of SM couplings with one loop full gravitational contributions in harmonic gauge, we study the constraints on the higgs and top quark mass from the requirement of existing the other degenerate vacua at the Planc…
We discuss the hierarchy problem and the corresponding quadratic divergences in the top mode Standard Model. Quadratic divergences appear at each order 1/N_c since fermionic and bosonic contributions are of different order 1/N_c. It is shown that the full dynamical system to all orders in 1/N_c admits a solution, where the sum of all quadratic divergent contributions disappears.
We propose a new mechanism in which all of the electroweak symmetry breaking is driven by a natural top quark condensate, produced by topcolor interactions at a multi-TeV scale. The scheme allows the observed top quark mass, and acceptable T and S parameters, by invoking a seesaw mechanism involving mixing of the top with an additional isosinglet quark.
The top quark may get its mass not from a fundamental scalar but a Nambu-Jona-Lasinio mechanism involving a strongly coupled gauge sector that triggers top-quark condensation. Forbidding a large hierarchy in the gap equation implies that top-quark condensation is a spectator to electroweak symmetry breaking, which must be accomplished mainly by another sector. The properties of the electroweak symmetry breaking scalars are identified. Production mechanisms and decay modes are studied. Unlike the standard model, the scalar degree of freedom most relevant to electroweak symmetry breaking can onl…
Models of top condensation can provide both a compelling solution to the hierarchy problem as well as an explanation of why the top-quark mass is large. The spectrum of such models, in particular topcolor-assisted technicolor, includes top-pions, top-rhos and the top-Higgs, all of which can easily have large top-charm or top-up couplings. Large top-up couplings in particular would lead to a top forward-backward asymmetry through $t$-channel exchange, easily consistent with the Tevatron measurements. Intriguingly, there is destructive interference between the top-mesons and the standard model w…
We show that quadratic divergences in top-quark condensation are cancelled when the tadpoles cancel. This latter cancellation is naturally implemented as the cancellation among the top-quark, Goldstone and Higgs contributions. We also calculate the bosonic correction terms to Gribov's mass formula for the Higgs boson. These reduce the prediction for M_H from 167 GeV to 132 GeV. The tadpole cancellation condition by itself is an independent condition on the mass of the Higgs boson which, in Gribov's U(1)_Y scenario, yields M_H \approx 117 GeV with large theoretical uncertainty. More generally, …
Predictions for the ratio $M_W/m_t$ arise in top condensation models from different methods. One type of prediction stems from Pagels--Stokar relations based on the use of Ward Identities in the calculation of the \GB decay constants and expresses $M_W$ in terms of integrals containing the dynamically generated mass function $Σ_t(p^2)$. Another type of prediction emerges from the renormalization group equations via infrared quasi--fixed--points of the running top quark Yukawa coupling. We demonstrate in this paper that in the limit of a high cutoff these two methods lead to the same prediction…
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 constra…
We develop the modification of the top - quark condensation scenario, in which the Higgs boson is composed of all Standard Model fermions. Within this scenario we suggest the phenomenological model with non - local four - fermion interactions in which at the distances of the order of $\sim 1/100$ GeV the theory is represented in terms of only one Majorana spinor that carries the $U(12)$ index and, in addition, belongs to the spinor representation of $O(4)$. The Standard Model fermions are the components of this spinor. The symmetry $U(12)\otimes O(4)$ is responsible for the one - loop relation…
We discuss the modified top quark condensation model proposed in \cite{VZ2015}. This construction was inspired by the top - seesaw scenario, in which the extra heavy fermion $χ$ is added that may be paired with the top quark. Besides, this model incorporates the ideas of the Little Higgs scenario, in which the $125$ GeV scalar particle appears as a Pseudo - Goldstone boson. This model admits (in addition to the $125$ GeV scalar boson $H$) the heavier scalar excitation $H^\prime$. We consider the region of parameters, where its mass is $M_{H^\prime} \sim 1$ TeV, the width of $H^\prime$ is $Γ_{H…
Topcolor and topcolor-assisted technicolor provide examples of dynamical electroweak symmetry breaking which include top-condensation, thereby naturally incorporating a heavy top quark. In this note we discuss the roles of the Nambu-Jona-Lasinio (NJL) and large-N approximations often used in phenomenological analyses of these models. We show that, in order to provide for top-condensation but not bottom-condensation, the top-color coupling must be adjusted to equal the critical value for chiral symmetry breaking up to O(1/N) in any theory in which the isospin-violating ``tilting'' interaction i…
Classical scale invariance represents a promising framework for model building beyond the Standard Model. However, once coupled to gravity, any scale-invariant microscopic model requires an explanation for the origin of the Planck mass. In this paper, we provide a minimal example for such a mechanism and show how the Planck mass can be dynamically generated in a strongly coupled gauge sector. We consider the case of hidden SU(N_c) gauge interactions that link the Planck mass to the condensation of a scalar bilinear operator that is nonminimally coupled to curvature. The effective theory at ene…
