Generalized dual symmetry of nonabelian theories, monopoles and dyons
  In the present talk we present an investigation of nonabelian SU(N) gauge theories, describing a system of fields with non--dual g and dual \tilde g charges and revealing the generalized dual symmetry. The Zwanziger type action is suggested. The renormalization group equations for pure nonabelian theories, in particular for pure SU(3)\times\widetilde{SU(3)} gauge theory (as an example) are analysed. We consider not only monopoles, but also dyons. The behaviour of the QCD total beta--function is investigated. It was shown that this beta--function is antisymmetric under the interchange \alpha\leftrightarrow\frac 1\alpha (here \alpha\equiv\alpha_s), and has zero ("fixed point") at \alpha = 1. Monopoles, or dyons, are responsible for the phase transition. Considering critical points at \alpha_1\approx 0.4 and \alpha_2\approx 2.5, we give an explanation of the freezing of \alpha_s. 
C.R. Das, L.V. Laperashvili, H.B. Nielsen