Quantum magnets, gauge theories, domain walls and anomalies

by Tin Sulejmanpasic (ENS Paris)

Thursday 8 Mar 2018, 14:15 → 15:15 Europe/Berlin

SR2

I will discuss setups of effective field theories which describe various spin systems. They can typically be expressed as U(1) gauge theories. Such theories may have 't Hooft, anomalies - an inability of a symmetry to be gauged - which must be matched by nontrivial ground states (i.e. they cannot be gapped and not have any long range order), which may involve discrete symmetries as well as space-time inversion symmetries. As a result such systems always have interesting IR physics. They either break some global symmetries, are gapless or have some long-range topological order. I will discuss some possible scenarios in 1+1D and 2+1D spin systems and quantum field theories that are believed to be their effective description. I will also discuss some scenarios in which domain walls in regimes with spontaneously broken discrete global symmetries may have a 't Hooft anomaly inflow, which must be matched by a nontrivial domain wall theory.