FLOW EQUATIONS FOR THE RELEVANT PART OF THE PURE YANG-MILLS ACTION

Wilson's exact renormalization group equations are derived and integra ted for the relevant part of the pure Yang-Mills action. We discuss in detail how modified Slavnov-Taylor identities control the breaking of BRST invariance in the presence of a finite infrared cutoff k through relations among different parameters in the effective action. In part icular they imply a nonvanishing gluon mass term for nonvanishing k. T he requirement of consistency between the renormalization group flow a nd the modified Slavnov-Taylor identities allows to control the self-c onsistency of truncations of the effective action.