A Model for the Lambda Transition of Helium 4

TL;DR

This paper introduces a new model for the lambda transition in liquid helium-4, incorporating phase-locked particle groups to explain specific heat singularity and superfluid density behavior, aligning well with experimental data.

Contribution

The model advances understanding by integrating phase correlations and localized functions, providing explanations for specific heat singularity and superfluid density that differ from ideal Bose gas predictions.

Findings

Explains the logarithmic specific heat singularity.

Fits experimental superfluid density data well.

Predicts a small nonzero entropy in the superfluid component.

Abstract

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.