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[en] Two questions are discussed: (1) are basic laws of motion invariant with respect to the switching of the direction of time? and (2) what are the consequences of any basic irreversibility? Attention is mostly focused on the decay of kaons neutral. The Karib-CPLEAR asymmetry is discussed. (Z.J.)

[en] In this article the author describes how the Brout-Englert-Higgs (BEH) mechanism is a step forwards in the perspective of the unification of fundamental forces

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[en] This chapter is mainly concerned with the weak couplings of quarks and leptons. Discusses elementary properties of quarks and leptons; renormalizable gauge theories; the fermion mass matrix and the structure of the weak currents; weak interactions of b and t quarks; the weak mixing angles; bounds on the weak mixing angles; weak decays of b and t; multilepton configurations in b and t decays; grand unified theories; the unification of weak, electromagnetic and strong interactions; the minimal model (SU(5)); fermion masses and constraints on the number of generations; proton decay; and bounds on the t-quark mass. Points out that the present theory of elementary particles is based on spin 1/2 fermions interacting with gauge fields and with Higgs bosons. Finds that the SU(5) scheme enables the prediction (shared also by other grand-unified schemes, such as the PatiSalam) that proton is unstable, with a lifetime within a couple of order of magnitudes from the present experimental limit

[en] A lecture is presented in which the structure of hadronic levels predicted in the most simple four quark model is illustrated. SU(4) supermultiplets, charmed particle masses, and charmonium states are covered. 25 references

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[en] Knowledge of the fundamental constituents of matter has greatly advanced, over the last decades. The standard theory of fundamental interactions presents us with a theoretically sound picture, which describes with great accuracy known physical phenomena on most diverse energy and distance scales. These range from 10^-16 cm, inside the nucleons, up to large-scale astrophysical bodies, including the early Universe at some nanosecond after the Big-Bang and temperatures of the order of 10² GeV. The picture is not yet completed, however, as we lack the observation of the Higgs boson, predicted in the 100-500 GeV range - a particle associated with the generation of particle masses and with the quantum fluctuations in the primordial Universe. In addition, the standard theory is expected to undergo a change of regime in the 10³ GeV region, with the appearance of new families of particles, most likely associated with the onset of a new symmetry (supersymmetry). In 1994, the CERN Council approved the construction of the large hadron collider (LHC), a proton-proton collider of a new design to be installed in the existing LEP tunnel, with an energy of 7 TeV per beam and extremely large luminosity, of ∝10³⁴ cm^-2 s^-1. Construction was started in 1996, with the additional support of the US, Japan, Russia, Canada and other European countries, making the LHC a really global project, the first one in particle physics. After a short review of the physics scenario, I report on the present status of the LHC construction. Special attention is given to technological problems such as the realization of the super-conducting dipoles, following an extensive R and D program with European industries. The construction of the large LHC detectors has required a vast R and D program by a large international community, to overcome the problems posed by the complexity of the collisions and by the large luminosity of the machine. (orig.)