We propose a new single superfield representation for mixed retarded and
advanced correlators for noninteracting disordered systems. The method is
tested in the simpler context of Random Matrix theory, by comparing with well
known universal behavior for level spacing correlations. Our method is general
and could be especially interesting to study localization properties encoded in
the mixed correlators of Quantum Hall systems.Comment: 13 pages including two figures, RevTex4. Improved version. Figures
changed. To appear in Journal of Physics