INFRARED ASYMPTOTICS OF THE FEYNMAN PROPAGATOR IN A SIMPLE NON-ABELIAN MODEL

The large-distance behavior of the Feynman propagator is investigated in a simple non-Abelian model of fermions and massless bosons that gen eralizes the model considered by Popov and Wu with isospin to the case of an arbitrary compact semisimple Lie group and space dimension d le ss than or equal to 4. The leading infrared approximation for the asym ptotic behavior is obtained by means of the renormalization-group meth od applied to the effective one-dimensional massless model that descri bes the eikonal approximation to the original field theory.