University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, September 20th 2019
12:30 pm:
Speaker: Luca Delacretaz (U. Chicago)
Subject: Spontaneous symmetry breaking as a higher-form anomaly

I will show that in many cases spontaneous symmetry breaking leads to the emergence of a higher-form symmetry that has a mixed anomaly with the original symmetry. The converse is also true: these mixed anomalies can be shown to require the existence of a massless particle that non-linearly realizes the symmetry. This perspective leads to an extension of Landau's paradigm for classifying phases that distinguishes for example both sides of the BKT transition and certain fractional quantum hall phases; it also streamlines the hydrodynamic treatment of symmetry-broken phases. I will mostly focus on the case where the group is U(1), but will also discuss certain extensions to non-abelian or discrete groups.

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