Quasi-Diffusion in a 3D Supersymmetric Hyperbolic Sigma Model
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- Disertori, M., Spencer, T. & Zirnbauer, M.R. Commun. Math. Phys. (2010) 300: 435. doi:10.1007/s00220-010-1117-5
We study a lattice field model which qualitatively reflects the phenomenon of Anderson localization and delocalization for real symmetric band matrices. In this statistical mechanics model, the field takes values in a supermanifold based on the hyperbolic plane. Correlations in this model may be described in terms of a random walk in a highly correlated random environment. We prove that in three or more dimensions the model has a ‘diffusive’ phase at low temperatures. Localization is expected at high temperatures. Our analysis uses estimates on non-uniformly elliptic Green’s functions and a family of Ward identities coming from internal supersymmetry.