Abstract
We discuss Ward identities for strongly interacting fermion systems described by Eliashberg-type theories. We show that Ward identities are not in conflict with the Migdal theorem and derive diagrammatically a Ward identity for a charge vertex both in a Fermi liquid and when a Fermi liquid is destroyed at quantum criticality. We argue that a Ward identity for the spin vertex cannot be obtained within the Eliashberg theory.
Original language | English (US) |
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Article number | 085113 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 72 |
Issue number | 8 |
DOIs | |
State | Published - Aug 15 2005 |