Kosterlitz-Thouless Transition in 2D Interacting Bose Systems

We explore the possibility of Kosterlitz-Thouless (KT) transition in interacting two-dimensional (2D) Bose systems. To go beyond mean-field theory and treat correlations, we use a Matsubara Green’s function method, and study scaling structure of the interacting Green’s function just above the transition. We use the Bose-Einstein condensation criterion that the chemical potential equals the self-energy at zero frequency and momentum, thereby making the spectrum gapless. We calculate numerically self-consistent solutions of self-energy to 2nd order in the interaction strength, for the entire range of momentum, k, and compare our findings with analytic results in the limits of low- and high-k. This allows us to calculate a universal scaling parameter (independent of interaction strength) in the scaling equation for critical density and critical temperature, as well as the critical temperature, and jump in superfluid mass density. We examine the possibility of applying this method to 2D dipolar Bose systems.