Detecting phase transitions from the high-temperature phase in systems with a small physical parameter - art. no. 052104

The critical temperature of a dilute Bose gas is obtained in terms of the a ssociated small gas parameter, by a unifying approach which treats three an d two spatial dimensions on equal footing. even though the superfluid phase transition is known to be driven by different mechanisms in three and two dimensions. Good agreement is found with the critical temperature obtained by recent Monte Carlo data in three dimensions and by previous analytic met hods in two dimensions, respectively. This approach is expected to apply mo re generally to systems where the many-body theory is controlled by a small physical parameter in the high-temperature phase.