Rescaled coherent state theory of the λ-transition in liquid He4

The quantum partition function for the interacting boson system is calculated using a complete set of rescaled coherent states in which the helium atom occupation numbers are rescaled with a large scale factor. There are terms in the statistical weights that do not vanish in the limit of infinite scale factor. These scale independent terms are shown to be in the familiar form of the Ginzburg-Landau model, and are explained as the result of condensation.