Nonuniversal effects in the homogeneous Bose gas - art. no. 063609

Effective field theory predicts that the leading nonuniversal effects in th e homogeneous Bose gas arise from the effective range for S-wave scattering and from an effective three-body contact interaction. We calculate the lea ding nonuniversal contributions to the energy density and condensate fracti on and compare the predictions with results from diffusion Monte Carlo calc ulations by Giorgini, Boronat, and Casulleras [Phys. Rev. A 60, 5129 (1999) ]. We give a crude determination of the strength of the three-body contact interaction for various model potentials. Accurate determinations could be obtained from diffusion Monte Carlo calculations of the energy density with higher statistics.