Polarization operator in QCD at finite temperatures and densities

The polarization operator for (QCD) at finite temperatures and densities is calculated in the ''one-loop'' approximation and its properties are investigated. The transversality of the polarization operator is verified explicitly and the different asymptotic forms of the polarization operator are found. The spectrum of both the transverse and the longitudinal excitations of the quark-gluon plasma is obtained and the influence of the gauge on the results is investigated. The relationship between the finite mass of the gluons at Tnot =0 and the infrared divergences of QCD that are important for quark confinement is discussed. A renormalization-group generalization of the results of the ''one-loop'' approximation is presented and the possibility of an experimental verification, in the strong interactions, of the correctness of the postulate of asymptotic freedom for QCD is discussed