Critical Behavior of a Dilute Interacting Bose Fluid

The crossover from critical behavior to ideal Bose-gas behavior in a dilute, weakly interacting Bose fluid at low temperatures is shown to be described by a scaling function depending on the temperature, density, and dimensionality. The results are applied to the experimental measurements of Crooker et al. on the superfluid density of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in Vycor glass. The satisfactory agreement obtained lends support to the model of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ in Vycor as a dilute, weakly interacting, three-dimensional Bose fluid.