  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 but nonzero entropy content of
the superfluid component.
