Chiral Symmetry Breaking and Nonperturbative Scale Anomaly in Gauge Field Theories

The nonperturbative dynamics of chiral and scale symmetry breaking in asymptotically free and non-asymptotically free (with an ultraviolet stable fixed point) vector-like gauge theories is investigated.In the two-loop approximation analytical expressions for the chiral and gluon condensates are obtained.The hypothesis about a soft behaviour at small distances of composite operators in non-asymptotically free gauge theories with a fixed point is put forward and substantiated.It is shown that in these theories the form of the scale anomaly depends on the type of the phase in coupling constant to which it relates.The two component conception of scale symmetry breaking in gauge theories is suggested.The mass relation for the singlet scalar fermion-antifermion bound state is obtained.The important ingredient of this approach is a large (d""'2) dynamical dimension of composite chiral fields.The application of this approach to QeD and technicolour models is discussed.