[en] The projects carried out by the department of theoretical physics comprise a broad spectrum of current and fundamental problems of elementary particle physics, especially the interaction of the two. The examinations carried out by the department of experimental physics concern themselves with the production and transformation processes of elementary particles, their features, interactions and their underlying physical laws. This includes the construction of detectors such as HEGRA for high-energy cosmic ray detection. Problems from the area of condensed matter were also dealt with. (DG)

[en] It is shown that in the two schemes with four massive neutrinos which are compatible with the results of all neutrino oscillation experiments, the probabilities of ν-bar disappearance and appearance in long-baseline experiments are severely constrained

[en] New results on anti ν + p charged-current events at 400 GeV are presented. The treatment includes inclusive results concentrating on anomalous distributions as well as results on the physics of the hadronic system. Multiplicity and various other distributions, strange particles, and cross sections are found. 20 references

[en] A number of neutrino-induced processes occurring in the field of an intense electromagnetic wave and in constant crossed fields are studied. Both processes due to the interaction of neutrinos with electrons, ν+e→ν+e and ν+e→ν+μ, and reactions of the type nu-bar+p→n+1⁺ and ν+n→p+1^- are studied. The expressions for the probabilities of these processes are obtained and their dependence on the parameters characterizing the external field and the particle energy is discussed

No abstract available

[en] Source theoretic structure functions, the q²-dependent form of Adler's sum rule, and the hypothesis of an improved scaling variable that covers the full range of q², correctly imply the asymptotic limit of the π^+-p cross sections, 23 mb, as well as the nature of approach of both cross sections to that limit. (Auth.)

[en] New results are presented on the observation of the proton inverse beta-decay in the underground laboratory near nuclear reactors. The preceeding results were substantially enriched by modes connected with successive shutdown of two from three reactors. Proton inverse beta-decay cross-section and limitations on the neutrino oscillation parameters are determined. 9 refs., 1 fig

[en] The quasi-elastic cross-sections sigmasub(el)sup(tot) and dsigma/dq² for the reactions (1) νn→μp and (2)antineutrinop→μsup(+)n have been measured by using the data of the ν Gargamelle collaboration. 687 ν events, candidates for reaction 1), and 476 antineutrino events, candidates for the reactions 2), have been used for the analysis. Because the ν and antineutrino interactions are on nuclei, suitable corrections for nuclear effects have been taken into account. In the framework of the ''usual'' V-A theory, by assuming for the axial form factor the dipolar form Fsub(A)(q²)=1.231/(1+q²/Msub(A)sup(2)), our data have been fitted to the differential cross-sections dsigma/dq² integrated over the ν and antineutrino energy spectra and to the total cross-section sigmasub(el)sup(tot) as a function of the ν, antineutrino energy to determine the best value for the parameter Msub(A)

[en] Energy dE/dlambda, charge dQ/dlambda and strangeness dS/dlambda fluxes in K⁺p interactions at 32 and 70 GeV/c, and π⁺p interactions at 32 GeV/c are studied in terms of the angular variable lambda=x/psub(T) (psub(T) is the transverse momentum, x is the Feynman variable). The data on dQ/dlambda and dE/dlambda are practically energy independent between 32 and 70 GeV/c and do not depend on incident particle. For inclusive non-diffractive, inclusive diffractive and exclusive non-diffractive jets, the fraction of charge in any angular region δΩ away from the central region is found to be proportional to the energy flux in the same interval. The data on dQ/dE versus lambda are compatible with some versions of dual models and agree also with the Lund Monte-Carlo model. In exclusive channels the average ratio dQ/dS is different from unity and amounts to dQ/dS = 0.78+-0.04, thus showing different probability for the kaon valence anti s and u quark fragmentations. The dQ/dlambda and dE/dlambda distributions in nondiffractive K⁺p reactions and ß(anti ß)p interactions are found to be very similar

[en] We have observed 22 events of the process anti νp→anti νp with a background expectation of 8 events. The neutral-current-to-charged-current ratio sigma (anti νp→anti νp)/sigma (anti νp→μ⁺n) is measured to be 0.2 +- 0.1 for 0.3< q²<0.9 (GeV/c)², where -q² is the square of the four-momentum transfer to the proton. When combined with our previous measurement of νp→νp, this yields a ratio sigma (anti νp→νp)/sigma (νp→νp) =0.4 +- 0.2, where the error is statistical, suggesting that a purely vector, neutral, hadronic current is unlikely