Gauge dependence of RG-improved perturbative QCD results is studied on the basis of coupled system of nonlinear differential equations for running coupling α s and running gauge ā in two-loop approximation. It is shown that gauge dependence can essentially influence UV asymptotic behaviour of α s and even destroy its asymptotic freedom. Possible implications of this phenomena are discussed.

The concept of quantum principle is introduced as a principle whose formulation is based on specific quantum ideas and notions. We consider three such principles, viz, those of quantizability, local gauge symmetry, and supersymmetry, and their role in the development of the quantum field theory (QFT). Concerning the first of these, we analyze the formal aspects and physical contents of the renormalization procedure in QFT and its relation to ultraviolet divergences and the renorm group. The quantizability principle is formulated as an existence condition of a self-consistent quantum version with a given mechanism of the field interaction. It is shown that the consecutive (from a historical point of view) use of these quantum principles puts still larger limitations on possible forms of field interactions.