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Résumé |
Metals are an interesting class of gapless quantum many-body systems. Many metals are described by the famous "Fermi liquid theory" at low temperatures, but there are also many metallic materials for which Fermi liquid theory is an inadequate description. In this talk, I will argue that a productive way to think about certain properties of metals, beyond Fermi liquid theory, is in the language of emergent symmetries and anomalies, thus importing ideas originally developed in the context of gapped topological phases of matter and their boundaries. From this point of view, I will show how to derive a vast generalization of Luttinger's theorem, the result that relates the volume enclosed by the Fermi surface of a Fermi liquid to the microscopic charge density. From this one can derive a number of consequences, including strong constraints on the emergent symmetry group of compressible metals. I also discuss implications for electrical resistivity. |
