No abstract available

No abstract available

[en] The author describes the CPsup(n-1) models stressing the analogy with QCD and shows in some detail how the 1/n expansion allows one to understand their main properties. In particular a phenomenological Lagrangian is derived describing the interaction of the lowest pseudoscalar mesons where, because of the U(1) axial anomaly, the singlet gets a mass which is not vanishing in the chiral limit. Using the analogy of these models with QCD, the author describes how one can construct in QCD for large n a phenomenological Lagrangian for the pseudoscalar mesons that includes the effect of the anomaly. From this Lagrangian it is easy to show that there is no U(1) problem and that one can reasonably well understand the low energy dynamics of the pseudoscalar mesons. Finally the author discusses the consequences of having a non zero theta vacuum in QCD and computes the amplitude of some CP violating processes as eta→2π and the electric dipole moment of the neutron using standard current algebra techniques. (Auth.)

[en] Symanzik's approach (1975) to the renormalization problem in nonrenormalizable theories has been applied as to give meaning to vertex functions (VF) in massless models which are renormalizable in d space-time dimensions and are not in d + epsilon, epsilon > 0, dimensions. The important technical role in this approach is played by ΛDVO for VF with multiple insertions. ΛDVO means differential vertex operations where differentiations are performed w.r.t. UV cutoff Λ which, in scalar models, enters into kinetic part of lagrangian as 1/2 Λ^-2phif²(phi) and this regularization buys renormalizability in some range of epsilon > 0. (Auth.)

[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] An introduction to Langevin equations (stochastic differential equations (SDE) with white noise terms) is presented. The author also discusses recently developed (matrix) continued fraction methods for solving certain types of SDE and their associated Fokker-Planck equations. Use of SDE in the field of quantum optics is considered

[en] The author discusses the status of Grand Unified Theories (GUTs) and Grand Unified Theories with Supersymmetry (SUSY-GUTs). The successes and failures of the standard model (SU(3)xSU(2)xU(1)) are reviewed. Then the minimal SU(5) GUT and its predictions are discussed. Some of the possible generalisations of SU(5) are introduced. Finally supersymmetric grand unification in the globally supersymmetric case and in the locally supersymmetric case (SUGRA GUTs) respectively are discussed. (Auth.)

[en] The laser microprobe LAMMA-500 is a new type of analytical instrument. It includes a laser microscope which permits optical observation as well as laser excitation of the sample to be analyzed with a lateral resolution of less than 1μm. The positive and negative ions thereby resulting from a sample volume of about 10^-13 cm³ are analyzed in a time-of-flight mass spectrometer. Each single laser shot allows a complete mass spectrum with a mass resolution of 500 to be recorded. Although the concept of LAMMA-500 is developed for the analysis of thin cuts and foils (<2μm) thicker specimens can be investigated with laser light at grazing incidence as well. All elements of the periodic system can be detected. A linear relationship has been found between the element concentration and the signal height over a range of four decades. For many elements the detection limits are in the sub-ppm range and hence reach the order of 10^-20 g. (Auth.)

[en] Quarks and gluons - the elementary quanta of quantum chromodynamics or QCD - are produced with perturbatively calculable rates in short distance processes. This is because of asymptotic freedom. These quanta produced at short distances are, in a sense, 'visible' as jets of hadrons. (The jets do not contain the colored QCD quanta if - as is assumed - color is confined. The jets contain only colorless hadrons). The distribution of these jets is the distribution of the original quanta, apart from fluctuations generated in the (long distance) jet formation process. The distribution of the jets can thus test QCD in a particularly clear way at the parton level, at distances of order 5 X 10^-16cm (PETRA/PEP energies). Topics are: confinement jet notions; perturbative QCD tests; gluon jets; and QCD multijet structure at high energy. (Auth.)