Abstract: I will discuss properties of phases of matter in systems with a global U(1) symmetry and a (possibly discrete) translation symmetry.

The low energy theory of such systems is strongly constrained by these symmetries. I will give a framework to understand such constraints in great generality, vastly generalizing old theorems. The most powerful constraint comes about if the system is compressible, in which case the low-energy theory must have a very large emergent symmetry group -- larger than any compact Lie group. A familiar example is a Landau Fermi liquid, whose properties I will revisit from a modern point of view of characterizing its emergent symmetry and the associated 't Hooft anomaly. Many, if not all, non-Fermi liquids will have the same emergent symmetry group/anomaly as a Fermi liquid (even though they could have very different dynamics), and this determines some of their universal properties. I will discuss the implications for understanding the famous "strange metal" physics observed in experiments in some condensed matter systems.

To connect to the HET Seminar via Zoom, please click the following link:

https://theias.zoom.us/j/92467790530?pwd=WUI3U1RCRCtYSjJyV1A2Vmx6dk81QT09

Meeting ID: 924 6779 0530