Hard - Soft Renormalization and the Exact Renormalization Group ∗
نویسندگان
چکیده
In gauge theories, after integrating over the hard modes, the Wilsonian functional depending on the soft fields satisfies effective Ward identities. We observe that, enlarging the Wilsonian functional in order to include hard fields, the effective Ward identities arise from a non-local symmetry between the hard and soft fields. Using the flow equation technique, we outline a proof in perturbation theory of the validity of these identities in massless QED. Infrared finiteness follows for arbitrary zero momentum renormalization conditions compatible with the effective Ward identities.
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