title: Levinson-like theorem for scattering from a Bose-Einstein condensate.
abstract: A relation between the number of bound elementary excitations of an atomic Bose-Einstein condensate and the phase shift of elastically scattered atoms is derived. Within the Bogoliubov model of a weakly interacting Bose gas this relation is exact and generalizes Levinson's theorem. Specific features of the Bogoliubov model such as complex energy and continuum bound states are discussed and a numerical example is given.
authors.affiliation: Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187 Dresden, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Brand
authors.forename: I
authors.initials: I
authors.lastname: Häring
authors.forename: J-M
authors.initials: JM
authors.lastname: Rost