title: Leading off-diagonal correction to the form factor of large graphs.
abstract: Using periodic-orbit theory beyond the diagonal approximation we investigate the form factor, K(tau), of a generic quantum graph with mixing classical dynamics and time-reversal symmetry. We calculate the contribution from pairs of self-intersecting orbits that differ from each other only in the orientation of a single loop. In the limit of large graphs, these pairs produce a contribution -2tau(2) to the form factor which agrees with random-matrix theory.
authors.affiliation: The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Gregory
authors.initials: G
authors.lastname: Berkolaiko
authors.forename: Holger
authors.initials: H
authors.lastname: Schanz
authors.forename: Robert S
authors.initials: RS
authors.lastname: Whitney