title: Evidence for universal four-body states tied to an Efimov trimer.
abstract: We report on the measurement of four-body recombination rate coefficients in an atomic gas. Our results obtained with an ultracold sample of cesium atoms at negative scattering lengths show a resonant enhancement of losses and provide strong evidence for the existence of a pair of four-body states, which is strictly connected to Efimov trimers via universal relations. Our findings confirm recent theoretical predictions and demonstrate the enrichment of the Efimov scenario when a fourth particle is added to the generic three-body problem.
authors.affiliation: Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, 6020 Innsbruck, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Ferlaino
authors.forename: S
authors.initials: S
authors.lastname: Knoop
authors.forename: M
authors.initials: M
authors.lastname: Berninger
authors.forename: W
authors.initials: W
authors.lastname: Harm
authors.forename: J P
authors.initials: JP
authors.lastname: D'Incao
authors.forename: H-C
authors.initials: HC
authors.lastname: Nägerl
authors.forename: R
authors.initials: R
authors.lastname: Grimm