Related papers: Patterns of Custodial Isospin Violation from a Com…
We analyze the tension between naturalness and isospin violation in the Lee-Wick Standard Model (LW SM), by computing tree-level and fermionic one-loop contributions to the post-LEP electroweak parameters and the Zbb coupling. The model is…
Using an effective Lagrangian approach, we perform a model-independent analysis of the interactions among electroweak gauge bosons and the third generation quarks, i.e. the Wtb, Ztt and Zbb couplings. After one imposes the known…
The electroweak symmetry may be broken by a composite Higgs which arises naturally as a bound state of the top quark if the standard model gauge fields and fermions propagate in extra dimenions. The top quark mass and the Higgs mass can be…
After a brief comment on the role of top quark in models of electroweak symmetry breaking (EWSB), I shall discuss what we know about top quark interaction and how to improve that knowledge. Since bottom quark is the weak isospin partner of…
A complete analysis of the electroweak precision observables is performed within a recently proposed minimal composite Higgs model, realized as a 5-dimensional warped compactification. In particular, we compute Z->bb and the one-loop…
We propose a dynamical model with a (2 + 1)-structure of composite Higgs doublets: two nearly degenerate composites of the fourth family quarks t' and b', $\Phi_{t^{\prime}} \sim \bar{t^{\prime}}_{R}(t^{\prime},b^{\prime})_L$ and…
We study precision electroweak constraints within a RS1 model with gauge fields and fermions in the bulk. The electroweak gauge symmetry is enhanced to SU(2)_L \times SU(2)_R \times U(1)_{B-L}, thereby providing a custodial isospin symmetry…
We investigate grand unified theories (GUTs) in scenarios where electroweak (EW) symmetry breaking is triggered by a light composite Higgs, arising as a Nambu-Goldstone boson from a strongly interacting sector. The evolution of the standard…
The presented results on top quark properties include measurements of the top quark pair charge asymmetry, the top quark polarization in pair production and single top production, the W helicity in top quark decays. Results of spin…
It has been recently argued that realistic models with warped extra dimensions can have Kaluza-Klein particles accessible at the Large Hadron Collider if a custodial symmetry, SU(2)_V \times P_{LR}, is used to protect the T parameter and…
The mechanism of the electroweak symmetry-breaking (EWSB) is studied in the context of the heavy top quark, whose large mass may provide a clue as to the mechanism which generates the mass of the $W^\pm$ and $Z$ bosons. As a result, it…
We present a class of composite Higgs models arising from a warped extra dimension that can satisfy all the electroweak precision tests in a significant portion of their parameter space. A custodial symmetry plays a crucial role in keeping…
Several extensions of the Standard Model require the burden of electroweak symmetry breaking to be shared by multiple states or sectors. This leads to the possibility of the top quark interacting with a scalar more strongly than it does…
We show that an effective field theory that includes non-standard couplings between the electroweak gauge bosons and the top and bottom quarks may yield negative contributions to both the S and T oblique radiative electroweak parameters. We…
In models of dynamical electroweak symmetry breaking which sensitively involve the third generation, such as top quark condensation, the effects of the new dynamics can show up experimentally in Z->b\bar{b}. We compare the sensitivity of…
In the context of the radiative electroweak symmetry breaking scenario, we investigate the implications of a heavy top quark mass, close to its infrared fixed point, on the low energy parameters of the minimal supersymmetric standard model.…
We study the effects of custodial symmetry violation in the Georgi-Machacek (GM) model. The GM model adds isospin-triplet scalars to the Standard Model in a way that preserves custodial symmetry at tree level; however, this custodial…
We study the phenomenology of models of electroweak symmetry breaking where the Higgs potential is dominated by a positive quadratic term destabilized by a tadpole arising from the coupling to an "auxiliary" Higgs sector. The auxiliary…
The standard model of electroweak interactions is reviewed, stressing the top quark's impact on precision tests and on determination of parameters of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Some opportunities for the study of CP…
Precise measurements of the properties of the top quark test the Standard Model (SM) and can be used to constrain new physics models. The top quark pair charge asymmetry is an asymmetry predicted to occur beyond leading-order QCD in the SM,…