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Diagrammatic Approach for the High-Temperature Regime of Quantum Hall Transitions

We use a general diagrammatic formalism based on a local conductivity approach to compute electronic transport in continuous media with long-range disorder, in the absence of quantum interference effects. The method allows us then to investigate the interplay of dissipative processes and random drifting of electronic trajectories in the high-temperature regime of quantum Hall transitions. We obtain that the longitudinal conductance σ_{xx} scales with an exponent κ=0.767\pm0.002 in agreement with the value κ=10/13 conjectured from analogies to classical percolation. We also derive a microscopic expression for the temperature-dependent peak value of σ_{xx}, useful to extract κ from experiments.