Effective Mass of Atom and Excitation Spectrum in Liquid Helium-4 at T=0 K

TL;DR

This paper uses a self-consistent Green functions approach to calculate the effective mass and excitation spectrum of liquid helium-4 at zero temperature, achieving good agreement with experimental data.

Contribution

It introduces a self-consistent method within the Green functions formalism to accurately compute the effective mass and excitation spectrum of helium-4 at T=0 K.

Findings

Effective mass of helium-4 atom is 1.58 times the bare mass.

Excitation spectrum aligns well with experimental results.

Sound velocity in liquid helium-4 is 230 m/s.

Abstract

A self-consistent approach is applied for the calculations within the two-time temperature Green functions formalism in the random phase approximation. The effective mass of He4 atom is computed as $m^*=1.58 m$. The excitation spectrum is found to be in a satisfactory agreement with the experiment. The sound velocity is calculated as 230 m/s. The temperature of the Bose-condensation with the effective mass taken into consideration is estimated as 1.99 K.