[en] The Monte Carlo simulation of Majorana fermions is discussed on the example of supersymmetric Yang-Mills (SYM) theory. (orig.)

[en] The perspectives of numerical simulations in supersymmetric quantum field theories with vector-like gauge symmetries are discussed. A numerical simulation algorithm for SU(2) gauge theory with gluinos is studied and the first results on the glueball-gluinoball spectrum are presented. (orig.)

[en] The computational cost of numerical simulations of QCD with light dynamical Wilson-quarks is estimated by determining the autocorrelation of various quantities. In test runs the expected qualitative behaviour of the pion mass and coupling at small quark masses is observed. (orig.)

[en] A new version of the two-step multi-boson algorithm is developed with different fermion actions in the multi-boson and noisy Metropolis steps. (orig.)

No abstract available

[en] Violations of universality of couplings in a vectorlike extension of the standard model with three heavy mirror fermion families are considered. The recently observed discrepancies betwen experiments and the standard model in the hadronic branching fractions R_b and R_c of the Z-boson are explained by the mixing of fermions with their mirror fermion partners. (orig.)

[en] The numerical simulation of domain wall quarks with the two-step multiboson (TSMB) algorithm is considered. The inclusion of single quark flavours, as required for strange quarks, is discussed. The usage of computer memory can be kept relatively low, independently of the order of polynomial approximations. Tests are performed with two flavours (N_f = 2) of degenerate quarks near the N_t = 4 thermodynamical cross over. (orig.)

[en] The recent discovery of charmed D and F mesons led to an accumulation of a lot of information on the weak decays of these particles. The facts known at present are generally consistent with the Glashow-Iliopoulos-Maiami scheme for the weak currents, which are predicted the fourth flavour of quarks, the charm. The weak decays of the charmed mesons are governed by SU(3) rules analogous to the Okubo-Zweig-Iizuka rule for strong decays. Such Su(3) rules are given for semileptonic and nonleptonic decays of strange and charmed mesons. These relations depend on the colour structure of currents in the nonleptonic case. (D.P.)

[en] The investigation of topological properties of the gauge field in a two-dimensional Higgs model can help in understanding anomalous fermion number violation. (orig.)

[en] Gribov copies of the vacuum in two dimensional compact U(1) lattice gauge models are constructed. On the basis of this a gauge fixing algorithm is developped, which finds the minimum of the sum of link field squares. Numerical experience in a two dimensional Higgs model with fixed length scalar field is reported and the extension to three and four dimensional U(1) and four dimensional SU(2) gauge theories is briefly discussed. (orig.)