The Gluon Propagator in Analytic Perturbation Theory
  The structure of the beta function of massless QCD is considered in analytic perturbation theory (APT). The two-loop analytic effective coupling is written in terms of the Lambert W function. The method of APT is applied to the gluon propagator in the Landau gauge. It is shown that there is an nonperturbative ambiguity in determination of the anomalous dimension function of the gluon field. One possible resolution of the ambiguity is presented. 
B. Magradze (Tbilisi Mathematical Institute)