0000000000446940
AUTHOR
Hidenori S. Fukano
Top-seesaw assisted technicolor model and a $m=126$ GeV scalar
We consider a model of strong dynamics able to account for the origin of the electroweak symmetry breaking and heavy quark masses. The model is based on a technicolor sector, augmented with topcolor and top-seesaw mechanism to assist in the generation of heavy quark masses. The low energy effective theory is a particular three Higgs doublet model. The additional feature is the possibility of the existence of composite higher spin states beyond the scalars, which are shown to be essential in this model to provide extra contributions in the higgs decays into two photons. We provide a detailed strategy and analysis how this type of models are to be constrained with the present data.
Top-seesaw assisted technicolor model with 126 GeV Higgs boson
We discuss a model which involves the top quark condensation and the walking technicolor. We focus on the scalar boson in such a model from the viewpoint of the observed scalar boson at the LHC.
Topcolor-like dynamics and new matter generations
We explore a scenarios where topcolor-like dynamics operates in the presence of fourth generation matter fields. Using the Minimal Walking Technicolor as a concrete basis for model building, we construct explicit models and confront them with phenomenology. We show that if a new QCD generations exist, both the top-bottom mass splitting as well as the splitting between bottom quark mass and the masses of the fourth generation quarks can be naturally explained within topcolor-like dynamics. On the other hand, the much studied Minimal Walking Technicolor model where only a fourth generation of leptons arise, also leads to a viable model.
Strong dynamics, minimal flavor and $R_b$
We discuss how models of electroweak symmetry breaking based on strong dynamics lead to observable contributions to the Z-boson decay width to bbbar pairs even in the absence of any extended sector responsible for dynamical generation of the masses of the Standard Model matter fields. These contributions are due to composite vector mesons mixing with the Standard Model electroweak gauge fields and lead to stringent constraints on models of this type. Constraints from unitarity of WW-scattering are also considered.
Constraining on dynamical electroweak symmetry breaking via R_b
New strong gauge interactions remain a viable source for the electroweak symmetry breaking. However, addressing the generation of fermion masses remains a challenge. A basic observable which provides stringent constraints on the flavor extensions of Technicolor-type models is the decay rate of the Z boson into a bbbar-pair. In this paper we provide a general framework to evaluate the resulting constraints on the technicolor theory level taking into account the contributions from the vector and axial vector mesons and discuss the consequences for phenomenology.
126 GeV Higgs boson in the top-seesaw model
We consider a model of dynamical electroweak symmetry breaking built on the idea of top-seesaw mechanism. The model features a fourth generation of vector-like QCD quarks responsible for the origin of the top-seesaw mechanism and leading to the natural explanation of the large splitting between the top and bottom quark masses. Motivated by the LHC data on the couplings of the Higgs boson, we include the entire third generation of Standard Model matter fields into the model. We determine the low energy effective theory and the resulting low energy spectrum of states, and constrain the model parameters with constraints from the precision electroweak data and from the requirement of a light sc…
Flavor constraints in a bosonic technicolor model
Flavor constraints in a bosonic Technicolor model are considered. We illustrate different sources for their origin, and emphasize in particular the role played by the vector states present in the Technicolor model. This feature is the essential difference in comparison to an analogous model with two fundamental Higgs scalar doublets.
A hybrid 4$^{\textrm{th}}$ generation: Technicolor with top-seesaw
We consider a model combining technicolor with the top quark condensation. As a concrete model for Technicolor we use the Minimal Walking Technicolor, and this will result in the appearance of a novel fourth generation whose leptons constitute a usual weak doublet while the QCD quarks are vectorlike singlets under the weak interactions. We carry out an analysis of the mass spectra and precision measurement constraints, and find the model viable. We contrast the model with present LHC data and discuss the future prospects.