A MODEL FOR THE LAMBDA-TRANSITION OF HELIUM

Guided by the analogy to the Bose-Einstein condensation of the ideal Bose gas (IBG) we propose a new model for the lambda-transition of liquid helium. Deviating from the IBG our model uses phase-ordered and localized single-particle functions. This means that finite groups of particles are assumed to be phase-locked. These phase correlations can be related to the singularity at the transition point and to the occurrence of the superfluid density. The model leads to the following results: 1) a possible explanation of the logarithmic singularity of the specific heat, 2) a characteristic functional form for the superfluid density which yields excellent fits to the experimental data, 3) a quantitative prediction of a small nonzero entropy content of the superfluid component.