Helium-4 Energy and Specific Heat in Superfluid and Normal Phase

TL;DR

This paper calculates the energy and specific heat of Helium-4 across a wide temperature range using an improved Green functions approach, accurately capturing behavior near phase transition points.

Contribution

It introduces an approximation that enhances the random phase approximation, accurately modeling Helium-4's thermodynamic properties across superfluid and normal phases.

Findings

Accurate specific heat behavior at low and high temperatures

Improved theoretical model for Helium-4 thermodynamics

Consistent results with experimental data

Abstract

The calculation of the He4 energy and specific heat is carried out in a wide temperature range within the two-time temperature Green functions approach. The approximation improving the random phase approximation is developed providing the correct behaviour of the calculated specific heat at the temperatures $0 < T/T_c < 0.65$ and $T/T_c> 1.32$ where $T_c$ stands for the phase transition point.