[en] A review of the non-shell renormalization scheme is given. I stress the analogy of this renormalization procedure with the ''usual'' one used in QED and discuss the differences. The calculation of some important parameters in the GWS-model is sketched. 15 refs. (author)

[en] The epsilon-expansion of the critical exponents for the N-vector model is now available up to order epsilon⁵. Using a summation method based on a Borel transformation and a mapping, we obtain from these epsilon-expansions new estimates for the critical exponents, quite consistent in two dimensions with the exact values of the Ising model and in three dimensions with the estimates previously obtained from the perturbative expansion at fixed dimension

[en] The paper shows that the modification of the electromagnetic zero-point energy inside a solid aluminum ball ia large enough to be detected by a feasible Eoetvoes-type experiment improved only a factor of 100 over earlier experiments. Because of the uncertainties surrounding the relationship of the zero-point energy to the cosmological constant and to renormalization effects in general relativity that such an experiment might give a non-null result. This would be a test of the weak equivalence principle and of general relativity itself in regard to a very special purely quantum-mechanical form of energy

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[en] An N = 2, 4, Yang-Mills theory with a soft breaking of the expanded supersymmetry is analyzed. With N = 4, there are no divergences in the mass renormalization in any order. With N = 2, the mass and charge renormalization constants are the same and contain only single-loop divergences. Calculations are carried out to two loops

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[en] Previously a linear representation of supersymmetry (Ss) was used in investigations of renormalizability. There auxiliary fields have been introduced in order that the Ss-algebra closes 'off-shell'. When the auxiliary fields are eliminated by their equations of motion, the Ss representation becomes nonlinear and Ss closes only 'on-shell'. Following O.Piguet and K.Sibold 1984 Ss is expressed through Ward identities which are formulated as functional variations of the generating functional of the Green functions. These functional operators form a closed algebra, a fact essential for the proof of renormalizability, which is given. It is not necessary to use a specific subtraction scheme in the Green functions. The procedure is applied to the Wess-Zumino model and the supersymmetric extension of the quantum electrodynamics. 15 refs. (qui)

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