Analytic framework for self-dual criticality in ${\mathbb{Z}}_k$ gauge theory with matter

Abstract

The deconfined phase of 2+1D ${\mathbb{Z}}_k$ gauge theory exhibits topological order, with $e$ and $m$ anyons that have a $2\ddot{I}€/k$ braiding phase. Proliferating either $e$ or $m$ drives Higgs or confinement transitions, respectively. At the multicritical point where these transitions meet, the theory enjoys an additional duality symmetry that exchanges $e$ and $m$ anyons. This symmetry forces anyons with nontrivial braiding to close their gaps simultaneously, giving rise to a critical theory that mixes strong interactions with mutual statistics. We propose an effective $\mathrm{U}(1)\times \mathrm{U}(1)$ gauge theory with a mutual Chern-Simons term at level $k$ to describe the vicinity of the multicritical point for $k\ge 4$. The emergence of a global ${\mathrm{U}(1)}^{\mathrm{top}}\times {\mathrm{U}(1)}^{\mathrm{top}}$ symmetry at the critical point imposes powerful constraints on universal properties of the phase transition. In particular, we show that (1) the lattice magnetic flux operator embeds as a conserved $\mathrm{U}(1)$ current with protected scaling dimension; (2) the first-order line emanating from the critical point for $k=2$ disappears generically for sufficiently large $k$; (3) the correlation length exponent approaches that of the 3D XY model with corrections of order $1/k^2$ in the large $k$ limit. These predictions can be tested in near-term numerical simulations and pave the way for a more general exploration of topological quantum criticality enriched with anyon-permuting symmetries.

5+$\hat{I}\mu$ pages, 15 page appendix, (2+4) figures. v2: published version