No abstract available

No abstract available

No abstract available

[en] This paper reports on Leon Van Hove contribution at CERN and in European science and technology in the field of quantum mechanics

[en] A great deal of interest, both theoretical and experimental, has been devoted recently to the study of high-energy interactions. This interest has been greatly stimulated by the valuable application of the results obtained by Regge in potential scattering to high-energy elastic scattering. This paper will discuss an approach to high-energy physics which is to some extent complementary to the one based on Regge poles and has the following features: (1) It is based on a model for high-energy interactions obtained as the natural generalization of the peripheral model which has been successful in understanding many features of interactions between 1~3 GeV. This model describes the high-energy collisions as the result of the combination of a large number of low-energy interactions. (2) The techniques used to evaluate the asymptotic limits are based on the direct study of the linear integral equations of the model and do not involve the use of analytic continuation in the angular momentum explicitly. (3) The model allows an estimate of the main features both of elastic diffraction scattering and of multiple production. The results concerning elastic scattering are closely analogous to the ones obtained on the basis of Regge poles. In order to explain the mathematical techniques in the simplest possible manner we have discussed in detail (Section 1 ) their application to potential scattering which is a very useful ''laboratory'' for theoretical physicists. Section 2 deals with the prediction of the model for elastic diffraction scattering and with the relativistic two-body equation. Finally in section 3 the different predictions concerning multiple production are discussed. The paper by Stroffolini is complementary to the present one since the mathematical techniques which can be used in order to evaluate the different ''trajectories'' both in potential scattering and in field theory are discussed there.

[en] The author gives an introduction to spontaneous symmetry breaking of Lagrangian field theories in the framework of the Higgs mechanism using chiral symmetry as an example. (HSI)

No abstract available

[en] This paper focuses on the nonrenormalizability of gravity as a quantum field theory. The approach used first ascribes the correct dimensionality to the field g /SUB munu/ ; second, interprets Newton's constant as a vacuum effect (this requires distinguishing between bound conditions and fundamental laws): and third, treats inverse operators. As a result of all this, gravitation should behave like a renormalizable theory: at small distances the Green functions of quantum gravity are substantially of a power form with the exponent determined by purely dimensional arguments

[en] The existence of self-dual instanton solutions of d = 4 Yang-Mills theories is related to the fact that the action can be expressed as the square of the self-dual field E + B. In this letter, we prove a similar result for d = 8 Yang-Mills theories. By use of the octonionic algebra the action can be represented as the sum of the squares of seven combinations of the field strengths. As a consequence, we construct a classical solution which is the eight-dimensional analogue of the d = 4 instanton. (orig.)

No abstract available