title: Nearest-neighbor distributions and tunneling splittings in interacting many-body two-level boson systems.
abstract: We study the nearest-neighbor distributions of the k -body embedded ensembles of random matrices for n bosons distributed over two-degenerate single-particle states. This ensemble, as a function of k , displays a transition from harmonic-oscillator behavior (k=1) to random-matrix-type behavior (k=n) . We show that a large and robust quasidegeneracy is present for a wide interval of values of k when the ensemble is time-reversal invariant. These quasidegenerate levels are Shnirelman doublets which appear due to the integrability and time-reversal invariance of the underlying classical systems. We present results related to the frequency in the spectrum of these degenerate levels in terms of k and discuss the statistical properties of the splittings of these doublets.
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Morelos, Mexico. saul@cicc.unam.mx
authors.forename: Saúl
authors.initials: S
authors.lastname: Hernández-Quiroz
authors.forename: Luis
authors.initials: L
authors.lastname: Benet