[en] In this talk I discuss the present status of these theories and of their observational and experimental implications. In section II, I briefly review the standard SU₃sup(c) x SU₂ x U₁ model of the strong and electroweak interactions. Although phenomenologically successful, the standard model leaves many questions unanswered. Some of these questions are addressed by grand unified theories, which are defined and discussed in Section III. The Georgi-Glashow SU₅ model is described, as are theories based on larger groups such as SO₁₀, E₆, or SO₁₆. It is emphasized that there are many possible grand unified theories and that it is an experimental problem not only to test the basic ideas but to discriminate between models. (orig./HSI)

[en] We report on recent results from two experiments on muon deep inelastic scattering at the CERN SPS, obtained with carbon targets by the BCDMS Collaboration, with iron, hydrogen and deuterium targets by the European muon collaboration. The energy of the muon varies from 120 to 280 GeV, and the accessible Q² range extends up to 200 GeV². (orig.)

[en] In this talk I review data on the formation of hadronic jets obtained in e⁺e^- collisions at the PETRA storage ring. The five large detectors CELLO, JADE, MARK J, PLUTO and TASSO have contributed to this subject. In the first part I concentrate on the evidence on QCD coming from the analyses of the e⁺e^- annihilation into three (or more) hadronic jets. The combined results on energy flow, momentum flow, parton thrust, angular distributions as well as a comparison with other jet production models show that indeed the QCD model is at present the only one which gives a satisfactory description of all available data. In the second part I discuss the present status of the determination of the strong coupling constant αsub(s). The problem here arises from the inclusion of the next to leading order corrections, O(α²sub(s)), to the one-gluon bremsstrahlung cross sections: there are two different approaches leading to different values of αsub(s). Finally I present some results concerning the behaviour of quark and gluon jets; there are indications that quarks and gluons fragment differently: hadrons from a gluon-jet seem to have a larger mean transverse momentum (at a given jet energy) than the hadrons from a quark jet. (orig.)

[en] Since the 1980 conference a large number of results on structure functions have been reported from neutrino experiments. New data are available from ν and anti ν scattering on protons and neutrons. Measurements of the cross section ratios sigmasup(νn)/sigmasup(νp) as function of energy and scaling variables x and y allow the extraction of differences between the u- and d-quark momentum distributions. Final results on structure functions from ν experiments on isoscalar targets exhibit clearly scaling violations. QCD fits to the data yield values of the scale breaking parameter Λ = 0.1-0.2 GeV. From a new measurement of the Q² evolution of the antiquarks together with F₂ data the gluon x distribution has been extracted. The discrepancies in the measurement of the total cross section are still unresolved. (orig.)

[en] Production of 2, 3, 4, and 5-muon final states by high-energy muons at Fermilab and CERN SPS is reviewed. Sixty-three 4μ, 5μ, and odd-sign 3μ final states have been observed. Corresponding limits on muoproduction of UPSILON, banti b, and anti M⁰ are summarized. Precise data on the Q² and ν-dependence of muoproduced elastic-psi, inelastic-psi, and open-charm states are presented. Elastic and inelastic psi muoproduction results are extended to include distributions in production and decay angle, elasticity, and momentum transfer to hadrons. Calculations using the lowest-order photon-gluon-fusion graph can be adjusted to reproduce the ν-dependence of elastic psi production, the ν and Q² dependence of open charm production, and the combined (hidden + open) charm production cross section. Unfortunately, the model does not account for the angular distributions and Q²-dependence observed for elastic psi production. Unless inhibited by order-of-magnitude threshold effects, the 'intrinsic charm' model predicts more copious open charm production at Bjorken x = 0.4 than is observed. Inelastic psi production exhibits half the pperpendicular to² slope observed for elastic psi production, with more similar dependence on Q² and ν. Shapes of the inelastic-psi distributions in ν and elasticity strongly favor calculations which use next-to-lowest-order photon-gluon diagrams explicitly conserving color and C-parity, when compared to those which do not. However, the favored diagrams account for only 18% of the observed cross section. (orig.)

[en] After a brief discussion of the equivalent photon approximations I review the theoretical foundation of various aspects of two photon physics. These aspects include resonance production, exclusive particle production, structure functions, and jet production. (orig./HSI)

[en] I report on two experiments performed this past year at PEP at a center-of-mass energy of 29 GeV. In the 'Free Quark Search Experiment', a specialized detector has been used to search in the debris of high energy e⁺e^- collisions for particles with fractional electric charge. The particular reaction studied so far is the two-body process e⁺e^- → qanti q. In the 'Highly Ionizing Particles Search Experiment' stacks of track recording plastic sheets have been used to detect magnetic monopoles or other particles with an ionization energy loss hundreds of times greater than that due to a minimum ionizing particle. (orig.)

[en] The current experimental status of charm production by neutrinos is reviewed. Recent results on like-sign dimuons are also discussed. (orig.)

[en] The author gives a review about the experimental study of the production of charmed and beautiful particles by neutrinos, photons, and hadrons. (HSI)

[en] The author gives a review of the experimental studies of the decay of charmed particles. (HSI)