Related papers: Limits on the anomalous $Wtq$ couplings
In the standard model, for the t --> W b decay mode, the relative phase is 0-degrees between the dominant A(0,-1/2) and A(-1, -1/2) helicity amplitudes. However, in the case of an additional large t_R --> b_L chiral weak-transition moment,…
We study and analyze the recent observations of the top pair production $\sigma (p\bar p\to t \bar t)$ at TeVatron through flavor conserving and flavor violating channels ${\it via}$ vector and tensor unparticles. The unparticle sector is…
We investigate a 5d gauge theory on $S^1$ with point interactions. The point interactions describe extra boundary conditions and provide three generations, the charged lepton mass hierarchy, the lepton flavor mixing and tiny degenerated…
D0 and CDF collaborations at the Fermilab Tevatron have searched for non-standard-model single top-quark production and set upper limits on the anomalous top quark flavor-changing neutral current (FCNC) couplings $\kappa^g_{tc}/\Lambda$ and…
Continuing earlier work, we examine the constraint on an anomalous t-c-g coupling from top quark decay. We find that from current CDF measurements of the branching ratio $t \rightarrow W b$, the minimum scale at which new physics can…
In the present study, we investigate the decays of the top quark $t\rightarrow c\gamma$, $t\rightarrow cg$, $t\rightarrow cZ$ and $t\rightarrow ch$. They are extremely rare processes in the Standard Model (SM). As the $U(1)$ extension of…
We study the sensitivity of the Large Hadron Collider (LHC) to anomalous tbW couplings in single-top production in association with a W^- boson followed by semileptonic decay of the top. We calculate top polarization and the effects of…
While rare meson decays place stringent constraints on much of the flavour violating parameter space of supersymmetric models, the mixing between right-handed top and charm squarks is so far unconstrained by the available data. Such mixing…
Large top quark flavor changing through neutral currents is expected by many extensions of the standard model. Direct and indirect searches for flavor changing neutral currents (FCNC) in the top quark decays to an up type quark (up,charm)…
The invisible variant axion model is very attractive as it is free from the domain wall problem. This model requires two Higgs doublets at the electroweak scale where one Higgs doublet carries a nonzero Peccei-Quinn (PQ) charge and the…
We investigate new physics effects on the Wtb effective couplings in a model-independent manner. The new physics effects are summarized as four independent couplings $f_1^L$, $f_1^R$, $f_2^L$ and $f_2^R$. Using single-top-quark productions…
The latest results on top quark physics, namely single top quark production cross sections, $W$-boson helicity and asymmetry measurements are used to probe the Lorentz structure of the $Wtb$ vertex. The increase of sensitivity to new…
This paper investigates the effects of parameters in the Bestest Little Higgs Model (BLHM) on rare flavor-changing decays of the top quark. As a result, flavor-changing phenomena are introduced in the BLHM for the first time. In this study,…
The flavor changing and CP violating phenomena predicted in supersymmetric unified theories as a consequence of the large top quark Yukawa coupling, are investigated in the quark sector and compared with related phenomena in the lepton…
The presence of the anomalous top quark flavour changing neutral current (FCNC) interactions leads to the production of same-sign top quarks in proton-proton collisions. The results of a search for events with same-sign dileptons and b-jets…
We investigate the potential of a high-energy $\gamma\gamma$ collider to detect an anomalous $\bar t q \gamma$ coupling from observation of the reaction $\gamma \gamma \to t\bar q$, $\bar t q$, where $q=c$ or $u$. We find that with…
The combination of the latest and most precise measurements of several top quark properties is presented in this paper in order to establish allowed regions on anomalous contributions to the Lorentz structure of the $Wtb$ vertex. These…
Flavour-changing neutral current (FCNC) interactions between the Higgs boson and the top quark are subject to significant suppression within the Standard Model (SM). Consequently, these interactions can only attain an observable level…
We demonstrate that flavour-changing neutral currents in the top sector, mediated by leptophilic scalars at the electroweak scale, can easily arise in scenarios of new physics, and in particular in composite Higgs models. We moreover show…
In this work, we investigate three typical new physics resonances which couple to the standard model (SM) quarks via direct top-quark flavor-changing interactions. We identify the possible SMEFT operators electroweak scale and analyze their…