Gauge invariance, background fields and modified Ward identities

Abstract

In this talk the gauge symmetry for Wilsonian flows in pure Yang-Mills theories is discussed. The background field formalism is used for the construction of a gauge invariant effective action. The symmetries of the effective action under gauge transformations for both the gauge field and the auxiliary background field are separately evaluated. Modified Ward-Takahashi and background field identities are used in my study. Finally it is shown how the symmetry properties of the full theory are restored in the limit where the cut-off is removed.

Comments: 6 pages, to appear in the Proceedings of the 2nd Conference on the Exact Renormalization Group, Rome 2000