Related papers: Multiscale Technicolor and the Zbb-bar Vertex
We examine the implications of the recent CDF measurement of the top-quark forward-backward asymmetry, focusing on a scenario with a new color octet vector boson at 1-3 TeV. We study several models, as well as a general effective field…
In this paper, we construct an effective model that describes the electroweak symmetry breaking sector by means of composite Higgs-like scalars, following the ideas of Minimal Walking Technicolor (MWT). We argue that, because of the general…
We revisit the possibility that the top quark forward-backward asymmetry arises from the on-shell production and decay of scalar top partners to top-antitop pairs with missing transverse energy. Although the asymmetry is produced by…
We consider the radiative decay $b\rightarrow s \gamma$, and the correction to the $Zb\overline{b}$ vertex in technicolor models with scalars. In these models, the scalar develops a vacuum expectation value when the technifermions condense,…
A study of the top quark \emph{Flavour Changing Neutral Current} (FCNC) through $Z$-boson has been performed in the proposed future $e^-p$ collider for the energy, $E_{e(p)} = 60~(7000)$~GeV. We considered an effective theory where the…
We examine the subprocess $\gamma\gamma \to t\bar{c}+\bar{t}c$ at electron-positron colliders in the two-Higgs-doublet model with flavor-changing scalar couplings, where all the one-loop contribuions are considered, and the results are…
Aspects of a flavor-changing W' model with right-handed couplings are addressed in this paper in light of Tevatron and LHC data. Our fit to the Tevatron top-quark forward-backward asymmetry and the tt_bar inclusive cross section includes…
New physics interactions can affect the strength and structure of the $tbW$ vertex. We investigate the magnitudes and phases of "anomalous" contributions to this vertex in a two-Higgs doublet and the minimal supersymmetric extension of the…
The top quark forward-backward asymmetry measured at the Fermilab Tevatron collider deviates from the standard model prediction. A W^prime boson model is described, where the coupling W^prime-t-d is fixed by the tt_bar forward-backward…
The top-charm associated productions via $e^+ e^-$, $e^- \gamma$ and $\gamma \gamma$ collisions at linear colliders, which are extremely suppressed in the Standard Model (SM), could be significantly enhanced in some extensions of the SM. In…
We explore the possibility to discriminate between certain strongly-coupled technicolor (TC) models and warped extra-dimensional models where the Standard Model fields are propagating in the extra dimension. We consider a generic QCD-like…
Due to the very large mass of the top-quark, probing the flavor changing top-charm-scalar vertex is clearly very important. Fortunately the largeness of $m_t$ endows a unique signature to the resulting reaction i.e., $e^+e^-\to t\bar c…
We investigate the production of beyond-the-standard-model color-sextet vector bosons at the Large Hadron Collider and their decay into a pair of same-sign top quarks. We demonstrate that the energy of the charged lepton from the top quark…
New colour octet vectors below the TeV scale could explain the anomalous t tbar forward-backward asymmetry observed at the Tevatron experiments, while being consistent with the current LHC data. These models generally lead to four-top final…
It has recently been shown that a new neutral vector boson $Z'$, with a mass of order 1~TeV and weak couplings to quarks only, could explain both the anomalous values of $R_b$ and $R_c$ and the apparent excess of large $E_T$ jet events…
We consider the contributions of the extra gauge boson Z' to the like sign $\tau$ production process $e^-\gamma\to e^+(\mu^+)\tau^-\tau^-$, induced by the tree-level flavor changing interactions. Since these rare production are far below…
Motivated by the recent unexpected large forward-backward asymmetry (FBA) of the top quark observed by D$\O$ and CDF at the Tevatron, we investigate a possible explanation for the anomaly within the framework of diquark models. Unlike other…
The Wtb vertex can be probed on future colliders in the processes of single top production (LHC, pp mode, NLC, $\gamma e$ mode) and of top pair production (NLC, e^+ e^- mode). We analyse observables sensitive to anomalous Wtb couplings in…
We calculate the rates for lepton number violating processes via the exchange of the Z' boson occuring in top-color assisted technicolor. The current experimental limits on muon electron conversion in Ti nuclei allow for a mass of the new…
Isodoublet color-octet scalar bosons appear in the low-energy limit of a natural extension of the Standard Model in which the electroweak symmetry is broken by a $t\bar t$ condensate. We briefly discuss the model and show that radiative…