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117 pp. (1997).

22 pp. (1990)., The author studies two-dimensional massless chiral QCD in a gauge invariant formulation. The Faddeev-Popov procedure is used to obtain a gauge invariant effective action after bosonisation, which is then quantised canonically using Dirac's prescription for constrained systems. The gauge current algebra is deduced and covariant current conservation is shown by means of the equations of motion of the bosonic matter fields.

35 pp. (1980).

11 pp. (1976).

55 pp. (1979)., The high energy behavior (in the Regge limit) of nonabelian gauge theories is reviewed. After a general remark concerning the question to what extent the Regge limit can be approached within perturbation theory, we first review the reggeization of elementary particles within nonabelian gauge theories. Then the derivation of a unitary high energy description of a massive (= spontaneously broken) nonabelian gauge model is described, which results in a complete reggeon calculus. There is strong evidence that the zero mass limit of this reggeon calculus exists, thus giving rise to the hope that the Regge behavior in pure Yang--Mills theories (QCD) can be reached in this way. In the final part of these lectures two possible strategies for solving this reggeon calculus (both for the massive and the massless case) are outlined. One of them leads to a geometrical picture in which the distribution of the wee partons obeys a diffusion law. The other one makes contact with reggeon field theory and predicts that QCD in the high energy limit is described by critical reggeon field theory.

(1977). doi:10.1063/1.523370, As a consequence of the geometrical features of dilations massless particles do not interact in a local, dilationally invariant quantum theory. This result also holds in models in which dilations are only a asymmetry of the S matrix.

26 pp. (1976).