Disordered free fermions and the Cardy Ostlund fixed line at low temperature

Abstract

Using functional RG, we reexamine the glass phase of the 2D random-field Sine Gordon model. It is described by a line of fixed points (FP) with a super-roughening amplitude $\overline{(u(0)-u(r){)}^2}\sim A(T){\ln }^{2}r$ as temperature $T$ is varied. A speculation is that this line is identical to the one found in disordered free-fermion models via exact results from ``nearly conformal'' field theory. This however predicts $A(T=0)=0$, contradicting numerics. We point out that this result may be related to failure of dimensional reduction, and that a functional RG method incorporating higher harmonics and non-analytic operators predicts a non-zero $A(T=0)$ which compares reasonably with numerics.

8 pages, 3 figures, only material added

References in corpus (1)

• Anomalous dimensions of operators without derivatives in the non-linear sigma-model for disordered bipartite lattices

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