Related papers: Non-commuting ETC corrections to zt\bar{t} vertex
In standard ETC models the sideways and diagonal ETC interactions contribute to $\delta R_b$ with opposite signs. The aim of this article is to study the implications of the CDF value for m_t and the LEP value for R_b on $zt\bar{t}$…
LEP precision measurements of the $Zb\bar{b}$ vertex coupling are sufficiently accurate to see the non-oblique corrections from the heavy gauge boson responsible for the large top mass in standard extended tecnicolour models. If the ETC…
We explore corrections to electroweak parameters in the context of Extended Technicolor (ETC) models in which the ETC gauge-boson which generates the top-quark mass carries weak $SU(2)$ charge. For $m_t \sim 150$ GeV there exist potentially…
We study the effect of the diagonal extended technicolor(ETC) gauge boson on the oblique correction parameters. It is shown that in the $T$ parameter is unacceptably large when the $Zbb$ vertex correction and $S$ parameter are consistent…
We propose a new \emph{CPT}-even and Lorentz-violating nonminimal coupling between fermions and Abelian gauge fields involving the CPT-even tensor $(K_{F})_{\mu\nu\alpha\beta}$ of the standard model extension. We thus investigate its…
The energy spectrum of the lepton(s) in e^+e^- --> tt-bar --> l^{+-} ...../l^+l^-..... at next linear colliders (NLC) is studied for arbitrary longitudinal beam polarizations as a possible test of new physics in top-quark couplings. The…
Using precision electroweak data, we put limits on non-commuting extended technicolor models. We conclude that these models are viable only if the ETC interactions are strong. Interestingly, these models predict a pattern of deviations from…
We analyze the corrections to the precision EW observables in minimal composite Higgs models by using a general effective parametrization which also includes the lightest fermionic resonances. A new, possibly large, logarithmically…
In the event that the Higgs mass is large or that the electroweak interactions are strongly interacting at high energy, top quark couplings to longitudinal components of the weak gauge bosons could offer important clues to the underlying…
The proposed Large Hadron Electron Collider (LHeC), with center-of-mass energy of $\sqrt{s}\approx 1.3$ TeV, provides a clean and sensitive environment to probe the top quark's neutral current interactions with the $Z$ boson via the process…
The process of top-quark pair production followed by semileptonic decays at future high-energy e^+e^- linear colliders is investigated as a possible test of physics beyond the Standard Model. Assuming the most general non-standard forms for…
We review the connection between $m_t$ and the $Zb\bar b$ vertex in ETC models and discuss the resulting experimental constraint on models with weak-singlet ETC bosons. We mention several recent efforts to bring ETC models into agreement…
In this work we investigate the NLO QCD+EW corrections to the top quark pair production and their effects on the spin correlation coefficients and asymmetries at fixed-order top quark pair production and LO decay in the dilepton channel,…
Extended technicolor theories generate potentially large corrections to the $\Zbb$ vertex which can be observed in current experiments at LEP.
We review the connection between $m_t$ and the $Zb\bar b$ vertex in ETC models and demonstrate the power of the resulting experimental constraint on models with weak-singlet ETC bosons. Some efforts to bring ETC models into agreement with…
It was reported that the NNLO correction to the total cross section near the ttbar threshold in e+e- collisions is as large as the NLO correction to it. In the thesis, we improve the convergence of the perturbative series of the total cross…
The precision of Cosmic Microwave Background (CMB) experiments, specifically its lensing reconstruction, has reached the limit where non-linear corrections cannot be ignored. Neglecting these corrections results in biased constraints on…
We compute, for $t \bar t$ production at the LHC and at the Tevatron, several charge asymmetries to NLO QCD, including also the electromagnetic and weak-interaction corrections. We calculate these asymmetries both inclusively and with…
We analyze LEP and SLC data from the 1995 Winter Conferences for signals of new physics. We compare the data with the Standard Model (SM) as well as a number of test hypotheses concerning the nature of new physics: (i) nonstandard Zbb…
We estimate the correction to the Zbb-bar vertex arising from the exchanges of the sideways extended technicolor (ETC) boson and the flavor-diagonal ETC boson in the multiscale walking technicolor model. The obtained result is too large to…