Effects of the T-matrix center-of-mass approximation in the Brueckner–Sawada theory of liquid helium II

1985 ◽  
Vol 63 (12) ◽  
pp. 1548-1554
Author(s):  
S. K. Bose ◽  
D. F. Goble
Keyword(s):  
Liquid Helium ◽  
Center Of Mass ◽  
Interacting Particles ◽  
Excitation Spectra ◽  
Helium Ii ◽  
Mass Approximation ◽  
Interparticle Separation ◽  
T Matrix ◽  
The Difference ◽  
Bose Einstein

As a model for liquid helium II, we study the Bose–Einstein gas with a two-body interaction potential of the form ~δ(r − a), where r is the interparticle separation. Excitation spectra for various values of a are calculated using the Brueckner–Sawada approach based on the concept of the T matrix. However, unlike the work of Brueckner and Sawada and many other related works that followed, we take into account the dependence of the T matrix on the center-of-mass momentum of the interacting particles. Excitation spectra calculated with and without this dependence, using two different expressions for the two-particle propagator, indicate the validity of the Brueckner and Sawada center-of-mass approximation for physically interesting values of a. The difference between the two spectra is found to increase as a increases.

Liquid helium and the properties of a Bose–Einstein gas. III. The density dependence of hard-core models

1970 ◽  
Vol 48 (11) ◽  
pp. 1340-1364
Author(s):  
D. F. Goble
Keyword(s):  
Density Dependence ◽  
Liquid Helium ◽  
Hard Core ◽  
Ladder Approximation ◽  
Model Systems ◽  
Coordinate Space ◽  
Core Boundary ◽  
T Matrix ◽  
Bose Einstein ◽  
Space Method

We have used the results of a previous paper by Goble and Trainor to compute the density dependence of the hard-core Bose–Einstein gas in the t-matrix ladder approximation, utilizing the coordinate-space method of Brueckner and Sawada as modified by Parry and ter Haar, and the pseudopotential treatment of the hard-core boundary condition presented by Liu and Wong. Various thermodynamic parameters of these model systems are compared with the properties of liquid helium four. The disagreements which are found are shown to be primarily related to differences in the magnitudes of the Landau parameters.

scholarly journals The Elementary Excitation Spectra of Liquid Helium II

1979 ◽  
Vol 61 (2) ◽  
pp. 367-383 ◽  
Author(s):  
K. Fukushima ◽  
N. Koyama ◽  
T. Sugiyama
Keyword(s):  
Liquid Helium ◽  
Elementary Excitation ◽  
Excitation Spectra ◽  
Helium Ii

Effect of an Excitation Energy on the Specific Heat of Liquid Helium II and Its Relation to the Exchange Effect in a Non-Ideal Bose-Einstein Gas

Nature ◽  
1939 ◽  
Vol 144 (3648) ◽  
pp. 594-595 ◽  
Author(s):  
A. MICHELS ◽  
A. BIJL ◽  
J. DE BOER
Keyword(s):  
Excitation Energy ◽  
Specific Heat ◽  
Liquid Helium ◽  
Exchange Effect ◽  
Helium Ii ◽  
Bose Einstein

Liquid Helium II: Bose-Einstein Condensation and Two-Fluid Model

1953 ◽  
Vol 92 (5) ◽  
pp. 1106-1112 ◽  
Author(s):  
P. R. Zilsel
Keyword(s):  
Liquid Helium ◽  
Fluid Model ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Helium Ii ◽  
Two Fluid Model ◽  
Bose Einstein ◽  
Two Fluid

THE THICKNESS OF MOVING HELIUM II FILM

1963 ◽  
Vol 41 (7) ◽  
pp. 1047-1055 ◽  
Author(s):  
P. W. F. Gribbon ◽  
L. C. Jackson
Keyword(s):  
Stainless Steel ◽  
Liquid Helium ◽  
Polarized Light ◽  
Helium Ii ◽  
The Difference ◽  
Stainless Steel Beaker ◽  
Moving Liquid

The thickness of moving liquid helium II films has been measured using the polarized light method developed by Burge and Jackson. The moving film was that on the outside of a cylindrical stainless steel beaker emptying by creep at the rate corresponding to the temperature for the two cases 1.68° K and 1.83° K. Measured at a height of 1 cm above the outer level of the liquid the thicknesses were 5.6% and 4.5% less than those of the stationary film at 1.68° K and 1.83° K respectively. The observations are compared with the theoretical expressions for the difference in thickness of stationary and moving films derived by Kontorovich and by Franchetti.

scholarly journals On the Bose-Einstein Liquid Model for Liquid Helium, II

1954 ◽  
Vol 11 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Ziro Mikura
Keyword(s):  
Liquid Helium ◽  
Helium Ii ◽  
Liquid Model ◽  
Bose Einstein

scholarly journals Multi-Branch Structure of the Excitation Spectra in Liquid Helium II

1973 ◽  
Vol 49 (6) ◽  
pp. 1802-1820 ◽  
Author(s):  
Takeji Kebukawa ◽  
Shuichiro Yamasaki ◽  
Sigenobu Sunakawa
Keyword(s):  
Liquid Helium ◽  
Excitation Spectra ◽  
Helium Ii

Surface Flow of Liquid Helium II and Bose-Einstein Degeneracy

Nature ◽  
1944 ◽  
Vol 153 (3881) ◽  
pp. 342-342 ◽  
Author(s):  
D. V. GOGATE ◽  
R. N. RAI
Keyword(s):  
Liquid Helium ◽  
Surface Flow ◽  
Helium Ii ◽  
Bose Einstein

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

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