[en] In these lectures we attempt to describe the final states of deep inelastic scattering as given by QCD. In the first section we shall briefly comment on the parton model and give the main properties of decay functions which are of interest for the study of semi-inclusive leptoproduction. The second section is devoted to the QCD approach to single hadron leptoproduction. First we recall basic facts on QCD log's and derive after that the evolution equations for the fragmentation functions. For this purpose we make a short detour in e⁺e^- annihilation. The rest of the section is a study of the factorization of long distance effects associated with the initial and final states. We then show how when one includes next to leading QCD corrections one induces factorization breaking and describe the double moments useful for testing such effects. The next section contains a review on the QCD jets in the hadronic final state. We begin by introducing the notion of infrared safe variable and defining a few useful examples. Distributions in these variables are studied to first order in QCD, with some comments on the resummation of logs encountered in higher orders. Finally the last section is a 'gaullimaufry' of jet studies

No abstract available

[en] In this note we make a phenomenological study of the recent EMC data on polarized structure function g₁^P(x). Using general principles like Regge behaviour and positivity we derive simple parametrizations for quark and gluon polarized distribution function and obtain a consistent description of experimental data

[en] The complete superspace geometry for Yang-Mills, chiral U(1) and Lorentz Chern-Simons forms is constructed. The analysis is completely off-shell and covers the cases of minimal, new minimal and 16-16 supergravity. Supersymmetry is guaranteed by construction. Invariant superfield actions are proposed

[en] We review some of the variables used in studying jets in leptoproduction: Sterman-Weinberg distributions, thrust, spherocity, pointing vectors and angular asymmetries

[en] It is studied how deeply group theory is involved in building grand unified theories, which embody electroweak and strong interactions. A particular aspect is considered: the Higgs problem

[en] It is shown that the non-linear Rsub(xi) gauge condition already introduced for the standard SU(2) x U(1) model can be generalized for any gauge model with the same type of simplification, namely the suppression of any coupling of the form: (massless gauge boson).(massive gauge boson).(unphysical Higgs)

[en] Using the standard model of cosmology we study the evolution of the population of a coupled system of two neutral fermions in which the lighter one is stable. During the expansion their population can be frozen at a certain level which makes them contribute to the mass density of the universe. The details of the freezing depend crucially on the couplings and on the masses of these two fermions, so that, comparison with the measured mass density in the universe gives constraints on the parameters of the physical system we examine. We discuss in detail different configurations for the couplings among these fermions; in particular in the case of large mixing we obtain restrictive bounds on both masses. Our study is relevant to supersymmetric grand unified models which predict the occurence of light interacting neutral fermions, particularly Higgsinos

[en] A method for flow pattern recognition has been developed for horizontal two-phase flow. Pressure drop and local void fraction signals are statistically analysed using the characteristic functions for air-water two-phase flow. A set of 'recognition parameters' is proposed and the variability range of each statistical parameter is tested in order to obtain a series of 'reference ranges' useful for recognition. An analysis of global recognition efficiency of the method is carried out. Very high resolution in flow pattern identification can be obtained and a wide possibility of applying to other fluid conditions is expected. (author)

[en] Using generalized Young tableaux, we obtain an explicit formula for the reduction of the Kronecker product of irreducible representation of the symplectic groups. This extends a previous work devoted to the case of orthogonal groups