Related papers: Top quark spin in ep collision
We present the full O(alpha_s) longitudinal spin-spin correlations for heavy-quark pair production at e+ e- high-energy colliders in closed analytical form. In such reactions, quark and antiquark have strongly correlated spins, and the…
We investigate the potential of $e\gamma$ collisions to probe anomalous $Wtb$ couplings via the polarized single top quark production process $e^{+} \gamma \to t \bar{b} \bar{\nu_{e}}$. We find 95% confidence level limits on the anomalous…
The LHeC is a proposed upgrade of the LHC to study $ep/eA$ collisions in the TeV regime, by adding a 60 GeV electron beam through an energy recovery linac. In $ep$, high precision top and electroweak physics can be performed, such as…
Linac-ring analogues of the LHC and VLHC based standard type ep collider proposals are discussed. It is shown that sufficiently high luminosities can be obtained with TESLA-like linacs, whereas essential modifications are required for CLIC…
Measurements of the top quark polarization and top quark pair ($\mathrm{t\bar{t}}$) spin correlations are presented using events containing two oppositely charged leptons (e$^+$e$^-$, e$^\pm\mu^\mp$, or $\mu^+\mu^-$) produced in…
Beam polarization at e+ e- linear colliders will be a powerful tool for high precision analyses. Often it is assumed that the full information from polarization effects is provided by polarization of the electron beam and no further…
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…
Electroweak dipole moments of the top quark are conjectured and their effect in polarized $e^+e^-$ collisions is examined for the expectation values of two different $CP$-odd observables. One of these observables probes the real part of the…
We investigate the potential of $\gamma\gamma$ collisions to probe scalar unparticle couplings via top-antitop quark pair production. We find 95% confidence level limits on the unparticle couplings with an integrated luminosity of $500…
A search for single top quark production is performed in e^\pm p collisions at HERA. The search exploits data corresponding to an integrated luminosity of 118.3 pb^-1. A model for the anomalous production of top quarks in a flavour changing…
Determination of the top-quark Yukawa couplings in the process e+ e- -> t \bar{t} Z has been studied for the high luminosity option (\int L=500\fbinver) of a linear e+e- collider. Polarization of the electron beam has been considered. The…
The presented results on top quark properties include measurements of the top quark pair charge asymmetry, the top quark polarization in pair production and single top production, the W helicity in top quark decays. Results of spin…
We consider top-antitop quark ($t{\bar t}$) production at the Large Hadron Collider (LHC) with subsequent decay into dileptonic and lepton plus jets final states. We present a set of leptonic angular correlations and distributions with…
We investigate the spin correlations in top quark pair production near threshold at the $ e^- e^+ $ linear collider. Comparing with the results above the threshold region, we find that near the threshold region the off-diagonal basis, the…
A large number of measurements with polarized beams and/or spin analysis of final state particles has been performed at the e^+e^- colliders LEP and SLC, providing important information on the dynamics of high energy interactions. In this…
The little Higgs models typically contain a new vector-like top quark $T$, which plays a key role in breaking the electroweak symmetry. In the context of the littlest Higgs (LH) model, we study single production of this kind of new particle…
The measurement of top quark spin correlation is an important tool for precise studies of top quark interactions. In this letter I construct a quantization axis maximizing the spin correlation at the LHC within the Standard Model. Using…
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…
We calculate the spin density matrix of top quark pairs for the reaction $e^+e^-\to t\bar{t}X$ to order $\alpha_s$. As an application we show next-to-leading order results for a variety of spin observables for the $t\bar{t}$ system. These…
Top quark pairs are produced with strongly correlated spins in the partonic reactions $q\bar{q}\to t\bar{t}$ and $gg\to t\bar{t}$. A complete description of these effects in terms of the spin density matrix of the $t\bar{t}$ system in…