The axino is a promising candidate for dark matter in the Universe. It is electrically and color neutral, very weakly interacting, and could be—as assumed in this study—the lightest supersymmetric particle, which is stable for unbroken R-parity. In supersymmetric extensions of the standard model, in which the strong CP problem is solved via the Peccei-Quinn… (More)
Top quark pairs are produced with strongly correlated spins in the partonic reactions q ¯ q → t ¯ t and gg → t ¯ t. A complete description of these effects in terms of the spin density matrix of the t ¯ t system in leading order QCD is given. We further discuss the prospects to observe the spin-spin correlations at p¯ p and pp colliders by measuring… (More)
We investigate the possibilities of searching for non-standard CP violation in pp → t ¯ tX at multiple TeV collision energies. A general kinematic analysis of the underlying partonic production processes gg → t ¯ t and q ¯ q → t ¯ t in terms of their density matrices is given. We evaluate the CP-violating parts of these matrices in two-Higgs doublet… (More)
We discuss rescattering effects that can be measured in e + e − annihilation to three jets through a single gauge boson, by using triple product (" event handedness ") correlations of the Z (γ *) polarization with jet momenta. The gauge boson polarization may be produced either by polarized beams or through the natural polarization (left-right asymmetry) of… (More)
We present a new layout algorithm for complex networks that combines a multi-scale approach for community detection with a standard force-directed design. Since community detection is computationally cheap, we can exploit the multi-scale approach to generate network configurations with close-to-minimal energy very fast. As a further asset, we can use the… (More)
Supersymmetry predicts the identity of Yukawa and gauge couplings in the QCD sector: q ˜ q˜g = ˜ q ˜ qg = qqg. We examine whether the q ˜ q˜g Yukawa coupling can be determined, by methods complementary to LHC, by analyzing squark-gluino final states at a TeV e + e − collider.
We discuss the angular distribution of the lepton pair in the Drell-Yan process, hadron + hadron → γ * + X → l + + l − + X. This process gives information on the spin-density matrix ρ (q,¯ q) of the annihilating quark-antiquark pair in q + ¯ q → l + + l −. There is strong experimental evidence that even for unpo-larised initial hadrons ρ (q,¯ q) is… (More)
I review progress on investigations concerning top quark physics and QCD at a future linear e + e − collider that has been achieved since the presentation of the TESLA technical design report  in spring 2001. I concentrate on studies that have been presented during the workshop series of the Extended Joint ECFA/DESY Study on Physics and Detectors for a… (More)
We compute the supersymmetric QCD corrections to the decay distribution of polarized top quarks for the semileptonic decay mode t(↑) → bl + ν l. As a byproduct, we reinves-tigate the SUSY-QCD corrections to the total decay width Γ(t → W + b) and resolve a discrepancy between two previous results in the literature.