Information about the Integer Quantum Hall Transition Extracted from the   Autocorrelation Function of Spectral Determinants
  The Autocorrelation function of spectral determinants (ASD) is used to probe the sensitivity of a two-dimensional disordered electron gas to the system's size L.   For weak magnetic fields ASD is shown to depend only trivially on L, which is a strong indication that all states are localized.   From nontrivial dependence of ASD on L for infinite L at a Hall conductance of 1/2 e^2/h we deduce the existence of critical wave functions at this point, as long as the disorder strength does not exceed a critical value. 
Stefan Kettemann (MPIPKS, Dresden), Alexei Tsvelik (University of   Oxford)