Related papers: Top Quark Polarization in Polarized $e^+e^-$ Annih…
Top quark pair production is presented at a polarized Muon Collider above the threshold region. The off-diagonal spin basis is the natural basis for this discussion as the top quark pairs are produced in an essentially unique spin…
We calculate the QED and QCD radiative corrections to the charged lepton energy distributions in the dominant semileptonic decays of the top quark $t \to b W^+ \to b(\ell^+ \nu_\ell)$ $(\ell=e, \mu, \tau)$ in the standard model(SM), and for…
Within the extended framework of the Two-Higgs-Doublet Model Type II (2HDM-II), enhanced by a vector-like quark (VLQ) doublet $TB$, we present a comprehensive analysis of the process $e^{-}\gamma \rightarrow b\nu_{e}\bar{T}$ at future…
Single top quark cross section evaluations for the complete sets of tree-level diagrams in the $e^+ e^-$, $e^- e^-$, $\gamma e$ and $\gamma \gamma$ modes of the next linear collider with unpolarized and polarized beams are performed within…
In this article we evaluate mass corrections up to $O((m^2/q^2)^6)$ to the three-loop polarization function induced by an axial-vector current. Special emphasis is put on the evaluation of the singlet diagram which is absent in the vector…
The cross-section for the production of $b{\bar b} c{\bar c}$ quarks in $e^+e^-$ annihilation, that proves to be at a level of $\sigma (e^+e^- \rightarrow b{\bar b} c{\bar c})/ \sigma (e^+e^- \rightarrow b{\bar b}) \sim 10^{-2}$ for ${\sqrt…
We calculate the next-to-next-to-leading order correction to the cross section for top quark pair production in e+e- annihilation in the threshold region, resumming all O [ (alpha_s/beta)^n (alpha_s^2, beta^2, alpha_s beta) ] terms of…
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…
We calculate the ${\cal O}(\alpha_s)$ radiative corrections to the spin dependent differential decay rates of the process $t\rightarrow b+W^+$. These are needed to study the angular distribution of the energy of hadrons produced in…
This paper presents the high-precision theoretical predictions for $e^+e^- \to l^-l^+$ scattering. Calculations are performed using the {\tt SANC} system. They take into account complete one-loop electroweak radiative corrections as well as…
On the basis of perturbative QCD and the relativistic quark model we calculate relativistic and bound state corrections in the production processes of a pair of S-wave and P-wave charmonium states. Relativistic factors in the production…
The cross section for different processes induced by $e^+e^-$ annihilation, in the kinematical limit $\beta_{\mu}\approx\beta_{\pi}=(1-m_{\pi}^2/\epsilon^2)^{1/2}\sim 1$, is calculated taking into account first order corrections to the…
Vector Leptoquarks (VLQs) have emerged as primary candidates for resolving discrepancies in the Standard Model, specifically within $B$-meson decay channels and the anomalous magnetic moment of the muon. This work presents a rigorous…
We investigate the single top quark production with the exchange of unparticles through high energy photon-photon collision $\gamma \gamma\to t \bar c$. The effects of unparticles on the scattering cross sections for different polarization…
The fragmentation of an unpolarized quark into a transversely polarized spin-1/2 particle is studied in the framework of a simple model. Special attention is payed to the gluon exchange which is incorporated in the gauge link of the…
Joint energy distribution of the bottom quark and antiquark from decays of the top quark and antiquark produced in the reaction $e^+ e^- \to t \bar{t}$ is studied. Main emphasis is put on $CP$-violation effects in the interaction of the…
We consider top quark production and decay in the narrow width approximation and study if the polarisation effects, that manifest themselves in correlations of angular distributions of particles from top quark decays and final state jets in…
Measurement of the helicity asymmetric cross section for semi-inclusive production of $\Lambda$-hyperons in $e^+e^-$ annihilation near the $Z^0$ resonance allows a complete determination of the spin-dependent fragmentation functions for the…
We consider, both for unpolarized and longitudinally polarized electron beams, the production of a top quark pair in e+e- collisions with subsequent semileptonic top and nonleptonic anti-top decay and vice versa and investigate optimized…
In this talk electroweak corrections related to the finite top quark lifetime to the total top pair threshold e+e- cross section at NNLL order are discussed. We include the absorptive parts in electroweak matching conditions of the NRQCD…