SPECTRAL STATISTICS BEYOND RANDOM-MATRIX THEORY

Using a nonperturbative approach we examine the large frequency asymptotics of the two-point level density correlator in weakly disordered metallic grains. We find that the singularities of the structure factor at the Heisenberg time (present for random matrix ensembles) are washed out when conductance is finite. The results are nonuniversal (they depend on the shape of the grain and on its conductance), though they suggest a generalization for any system with finite Heisenberg time.