title: Dilute Bose-Einstein condensate with large scattering length.
abstract: We study a dilute Bose gas of atoms whose scattering length a is large compared to the range of their interaction. We calculate the energy density E of a homogeneous Bose-Einstein condensate (BEC) to second order in the low-density expansion, expressing it in terms of a and a second parameter Lambda* that determines the low-energy observables in the three-body sector. The second-order correction to E has a small imaginary part that reflects the instability due to three-body recombination. In the case of a trapped BEC with large negative a, we calculate the coefficient of the three-body mean-field term in E in terms of a and Lambda*. It can be very large if there is an Efimov state near threshold.
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Braaten
authors.forename: H-W
authors.initials: HW
authors.lastname: Hammer
authors.forename: Thomas
authors.initials: T
authors.lastname: Mehen