相关论文: On the top-quark polarization and how to measure i…
Top quark polarization in $e^+e^-$ annihilation into $t\bar t$ is calculated for linearly polarized beams. The Green function formalism is applied to this reaction near threshold. The Lippmann--Schwinger equations for the $S$-wave and…
Polarization studies for heavy quarks can lead to important tests of the Standard Model. Top quark pair production in $e^+e^-$ annihilation is considered near energy threshold. It is shown that for longitudinally polarized electrons the…
Longitudinal polarization of the top quark, averaged over the production angle, is discussed for the top quark produced in e+e- annihilation near its production threshold. It is demonstrated that Coulomb type corrections and rescattering…
Electron-positron annihilation into a pair of top quarks is considered at the energy of the future collider CLIC. Polarization components of the top quark are calculated with the $\gamma t \bar{t}$ and $Z t \bar{t}$ interactions which…
We discuss in detail top quark polarization in above-threshold (t \bar t)-production at a polarized linear e^+ e^- collider. We pay particular attention to the minimization and maximization of the polarization of the top quark by tuning the…
We present the results of an O(alpha_s) calculation of the transverse polarization of top quarks produced in e+e- annihilation. In a first step we determine the transverse polarization of the top with regard to the hadron plane spanned by…
The polarization of a top-quark can be sensitive to new physics beyond the standard model. We propose a novel method to measure top-quark polarization, based on the charged lepton energy fraction in top-quark decay, and illustrate the…
We discuss the polarization of top quarks produced at a polarized linear e^+ e^- collider. Close-to-maximal values of the top quark polarization can be achieved with longitudinal beam polarizations (h_- = -0.80, h_+ = +0.625) or (h_- =…
Measuring top polarization is extremely important in understanding any new physics that couples to top quark. Here, we take up the task of extracting polarization of top quark coming from TeV-scale stop decay at the upgraded high luminosity…
Recent results on production and decays of polarized top quarks are reviewed. Top quark pair production in $e^+e^-$ annihilation is considered near energy threshold. For longitudinally polarized electrons the produced top quarks and…
In most of the models beyond the Standard Model, the top quark is expected to be polarized when produced in the decay of some heavier particle, like the gluino or the stop. The polarization is constructed, in an experiment or in…
Top quark studies at future $e^+e^-$ colliders are considered. Two issues are discussed: {a --}Some results are presented on the decays of top quarks. Energy distributions of charged leptons and neutrinos in $t\to bW\to be^+\nu$ and jets in…
We analyze the pair-production of top quarks in polarized $e^+e^-$ scattering in the presence of electroweak dipole moments. For this, we consider two $CP$-odd observables which probe both the real and the imaginary parts of these moments.…
We show that the longitudinal polarization of the top quarks produced in the annihilation of e+ e- or mu+ mu- into tbar t at energies near the threshold is not affected by the large Coulomb-type corrections, which greatly modify the total…
We consider the decay of a polarized top quark into a polarized W-boson plus a bottom quark, followed by the decay of the W-boson into a pair of leptons or quarks. The polar angle distribution of the top spin relative to the W-momentum and…
An optimal-observable analysis of the angular and energy distributions of the leptons and bottom quarks in the process e+e- --> tt-bar --> l^{+-}/b(b-bar)... has been performed in order to measure the most general top-quark couplings to…
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…
Theoretical results are presented for top quarks produced in annihilation of polarized electrons on positrons. Polarization studies for $t\bar t$ pairs near threshold are free from hadronization ambiguities. This is due to the short…
Measuring the top quark mass in its semileptonic decay mode, $t ->be^+\nu$ ($b -> \mu^- + X$), through the mass distribution of the $e^+$--$\mu^-$ pair has been shown to provide a good measurement of the top quark mass with an uncertainty…
We review the physics involved in the production and decay of top quarks in e^+e^- -> ttbar near threshold, with special emphasis on the recent theoretical study on the decay process of top quarks in the threshold region. The energy-angular…