[en] The author abstracts some general features from symmetry models for the Yukawa-interactions of quarks. The successful relation tg²thetasub(C)=d/s (thetasub(C) is the Cabibbo-angle, d and s are the masses of the down-quark and the strange-quark) is incorporated into a model for 6 flavours (u,d,c,s,t,b), arranged in three left-handed doublets. If the CP-violation is determined by the generalized GIM-matrix with a 'naturally' large phase, one is led to the 'prediction' 9 < approximately t < approximately 13 GeV for the mass of the top-quark. The new mixing angles turn out to be very small (<=thetasub(C)/10). In anticipation of this result a simple phenomenology is also developed, which at small angles may be more useful than the standard one by Kobayashi and Maskawa. (Auth.)

No abstract available

No abstract available

[en] Dimensional reduction of generalized gravity theories or string theories generically yields dilaton fields in the lower-dimensional effective theory. Thus at the level of D=4 theories and cosmology, many models contain more than just one scalar field (e.g., inflaton, Higgs, quintessence). Our present work is restricted to two-dimensional gravity theories with only two dilatons which nevertheless allow a large class of physical applications. The notions of factorizability, simplicity and conformal simplicity, Einstein form, and Jordan form are the basis of an adequate classification. We show that practically all physically motivated models belong either to the class of factorizable simple theories (e.g., dimensionally reduced gravity, bosonic string) or to factorizable conformally simple theories (e.g., spherically reduced scalar-tensor theories). For these theories a first order formulation is constructed straightforwardly. As a consequence an absolute conservation law can be established

[en] The author deals with superalgebras, superfields, the fermion number, supersymmetry, the construction of a gauge Lagrangian and the problem of the Goldstone fermion. Prototype models of weak and electromagnetic interactions are outlined. (Auth.)

No abstract available

[en] Short communication

[en] The role of scalar bosons is studied in connection with a violation of the number of fermions + antifermions. Some simple estimates of the transitions μ→eγ and μ→3e are based upon a minimal extension of the 'standard' gauge model of weak and electromagnetic interactions. (Auth.)

[en] Anomalies related to an external global symmetry of the gauge-fixed action may well possess relevance in physical observables. Their gauge-(in-)dependence is most suitably controlled by a combination of the BRS-technique which includes a BRS-transformation of the gauge-parameters, with the external symmetry coupled to an external gauge field. For an external symmetry which commutes with BRS, anomalies are shown to be essentially gauge-independent (to one loop order). A nontrivial example is the ghost number anomaly of the bosonic string. However, e.g. the anomalies of superconformal transformations do not fall into this category. 12 refs. (author)

[en] For a long time the homogeneous axial gauge has been known to be free of Faddeev-Popov ghosts. Nevertheless, only recently in a systematic study using modern field-theoretic methods has it been shown by the authors that the S-matrix is covariant (gauge-independent) and unitary in such a 'singular' gauge. This gauge is particularly well adapted to discuss the problem of mixing of gauge-invariant operators, the latter being important for the discussion of the small distance behaviour in asymptotically free theories of strong interactions. Here a theoretical basis for calculations in space-like or time-like axial gauges is given. By-products of the considerations are the proof of Lorentz covariance for the counterterms in the renormalized Lagrangian, for the parameters of spontaneous symmetry breaking and for the functions in renormalization group equations in such a non-covariant gauge. (Auth.)