Harmonically trapped four-boson system

D. Blume, M. W. C. Sze, J. L. Bohn
2018 Physical Review A  
Four identical spinless bosons with purely attractive two-body short-range interactions and repulsive three-body interactions under external spherically symmetric harmonic confinement are considered. The repulsive three-body potential prevents the formation of deeply-bound states with molecular character. The low-energy spectrum with vanishing orbital angular momentum and positive parity for infinitely large two-body s-wave scattering length is analyzed in detail. Using the three-body contact,
more » ... tates are classified as universal, quasi-universal, or strongly non-universal. Connections with the zero-range interaction model are discussed. The energy spectrum is mapped out as a function of the two-body s-wave scattering length a_s, a_s>0. In the weakly- to medium-strongly-interacting regime, one of the states approaches the energy obtained for a hard core interaction model. This state is identified as the energetically lowest-lying "BEC state". Structural properties are also presented.
doi:10.1103/physreva.97.033621 fatcat:7zi5kvqcc5eejdchhirlstw6ue