Universality in Quantum Hall Systems: Coset Construction of Incompressible States
J. Froehlich, B. Pedrini, C. Schweigert, J. Walcher
TL;DR
The paper builds a unified CCFT/TFT framework for incompressible QHFs, identifying how bulk Chern-Simons data map to edge CCFT data and imposing consistency, modular-covariance, and stability criteria to select viable theories. It introduces a constructive program based on simple currents and coset techniques to generate CCFTs describing QHFs with rational Hall conductivities, and shows explicit coset-based examples that reproduce known plateaux such as $\sigma_H = \frac{1}{2}\frac{e^2}{h}$, $\frac{1}{4}\frac{e^2}{h}$, $\frac{3}{5}\frac{e^2}{h}$, and $\frac{e^2}{h}$. The work connects quantum Hall lattices to CCFT data, provides methods to gauge symmetries via cosets, and presents Virasoro minimal-model and simple-current extension realizations (including Ising-related states) as concrete candidates for incompressible QHF descriptions. Overall, the framework offers a systematic route to classify and construct incompressible QHF states and to understand their bulk-edge correspondence through rational CCFTs and their associated TFTs.
Abstract
Incompressible Quantum Hall fluids (QHF's) can be described in the scaling limit by three-dimensional topological field theories. Thanks to the correspondence between three-dimensional topological field theories and two dimensional chiral conformal field theories (CCFT's), we propose to study QHF's from the point of view of CCFT's. We derive consistency conditions and stability criteria for those CCFT's that can be expected to describe a QHF. A general algorithm is presented which uses simple currents to construct interesting examples of such CCFT's. It generalizes the description of QHF's in terms of Quantum Hall lattices. Explicit examples, based on the coset construction, provide candidates for the description of Quantum Hall fluids with Hall conductivity s_H=1/2 e^2/h, 1/4 e^2/h, 3/5 e^2/h, e^2/h,...
