Transition temperature for weakly interacting homogeneous Bose gases - art. no. 014515

We apply the nonperturbative optimized linear delta expansion method to the O(N) scalar field model in three dimensions to determine the transition te mperature of a dilute homogeneous Bose gas. Our results show that the shift of the transition temperature DeltaT(c)/T-c of the interacting model, comp ared with the ideal-gas transition temperature, really behaves as gamma an( 1/3) where a is the s-wave scattering length and n is the number density. F or N = 2 our calculations yield the value gamma = 3.059.