2004/02/29 by A. A. Katanin · 7 citations
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum Chromodynamics and Particle Interactions #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.70.115109
published as Phys. Rev. B 70, 115109 (2004) · 4 pages, 1 figure, RevTex
arxiv created 2004/04/24 · openalex publication_date 2004/09/23 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We consider the fulfillment of conservation laws and Ward identities in the one- and two-loop functional renormalization group approach. It is shown that in a one-particle irreducible scheme of this approach Ward identities are fulfilled only with the accuracy of the neglected two-loop terms O(V_\ensuremathΛ3) at one-loop order, and with the accuracy O(V_\ensuremathΛ4) at two-loop order (V_\ensuremathΛ is the effective interaction vertex at scale \ensuremathΛ). The one-particle self-consistent version of the two-loop renormalization group equations which leads to smaller errors in Ward identities due to the absence of the terms with nonoverlapping loops, is proposed. In particular, these modified equations exactly satisfy Ward identities in the ladder approximation.