Phases of 2d gauge theories and symmetric mass generation

A bstract We study the dynamics and phase structure of Abelian gauge theories in d = 1 + 1 dimensions. These include U(1) gauge theory coupled to a scalar and a fermion, as well as the two-flavour Schwinger model with different charges. Both theories exhibit a surprisingly rich phase diagram as masses are varied, with both c = 1 and c = 1/2 critical lines or points. We build up to the study of 2d chiral gauge theories, which hold particular interest because they provide a mechanism for symmetric mass generation, a phenomenon in which fermions become gapped without breaking chiral symmetries.