Global aspects of covariant quantization of gauge theories

A global analysis of the covariant formulation of gauge theories shows that nonperturbative effects give rise to anomalous contributions to the Slavnov-Taylor identities. However, a global geometrical interpretation of BRST symmetry can be formulated and its relation with Slavnov-Taylor identities is clarified by means of this interpretation. In particular, we show that the existence of those non-perturbative anomalies in the Slavnov-Taylor identities does not imply a breaking of BRST symmetry. This opens the possibility of a BRST approach to the Osterwalder-Schrader construction of the physical states of the theory in the covariant formalism.