Wigner-Dyson statistics from the Keldysh sigma-model.
The level statistics of disordered metallic grains with broken time reversal invariance is obtained from the Keldysh nonlinear sigma-model. The basic strategy of the approach--a nonperturbative integration over all saddle points of the sigma-model manifold--might prove useful in the analysis of problems involving disorder and interactions.
Altland
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Theoretische Physik III, Ruhr-Universität Bochum, 44780, Germany.
Kamenev
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