CRITICAL-TEMPERATURE OF BOSE-EINSTEIN CONDENSATION OF HARD-SPHERE GASES

We determine the critical temperature of a 3D homogeneous system of ha rd-sphere bosons by pathintegral Monte Carlo simulations and finite-si ze scaling. In the low density limit, we find that the critical temper ature is increased by the repulsive interactions, as Delta T-C/T-0 sim ilar to (na(3))(gamma), where gamma = 0.34 +/- 0.03. At high densities the result for liquid helium, namely, a lower critical temperature th an in the noninteracting case, is recovered. We give a microscopic exp lanation for the observed behavior. [S0031-9007(97)04438-4].