Critical temperature of the superfluid transition in Bose liquids

A phenomenological criterion for the superfluid transition is proposed, which is similar to the Lindemann criterion for the crystal melting. Then we derive a formula for the critical temperature, relating Tx to the mean kinetic energy per particle above the transition. The suppression of the critical temperature in a sufficiently dense liquid is described as a result of the quantum decoherence phenomenon. The theory can account for the observed dependence of T-lambda on density in liquid helium and results in an estimate T(lambda)similar to 1.1 K for molecular hydrogen. [S0163-1829(99)08529-X].