Conformal anomalies in quantum chromodynamics and the path-integral method

The foundation of the path-integral derivation of anomalies is investigated. The combined use of zeta-function regularization and the background-field method clarifies the generality as well as limitations of the path-integral method and reveals the way to treat nonlinear systems. As an application, a detailed study of conformal anomalies in quantum chromodynamics is presented. By virtue of background gauge covariance the conformal Ward-Takahashi identities are cast into an equivalent background covariant form suited for the actual calculation of the anomaly.