Critical temperature of trapped hard-sphere Bose gases

We determine the critical temperature of parabolically trapped hard-sphere bosons via path-integral quantum Monte Carlo calculations of the condensate fraction and the specific heat. Contrary to previous predictions, the critical temperature of the weakly interacting gas remains roughly constant with respect to increases in the hard-sphere diameter, and is approximately equal to the critical temperature for ideal bosons. As the hard-sphere diameter is increased further, the critical temperature eventually begins to decrease. We give an explanation for the discrepancy between previous results and those presented here. [S1050-2947(98)03512-0].