Theory of structure and thermodynamic function of liquid 4He (Review Article)

Abstract

A new method of calculation of the density matrix of a many-boson system is proposed. The calculation of thermodynamic and structure functions at finite temperatures based on density matrix of Bose liquid is made. The structure factor of liquid 4 He at T = 0 K is used as an input information for numerical calculation instead of the interatomic potential. We found a good agreement of the calculated quantities with experimental data.

Polaron in the dilute critical Bose condensate

“…[36] the perturbative second-order energy correction and the damping were found to increase enormously near the BEC temperature. On the other hand, from the theory of the critical Bose systems it is known [37] that the reliable result for the one-particle spectrum can be obtained only with an infinite series of diagrams taken into account. In the present article by means of the 1/N -expansion, which effectively incorporates bosonic "particle-hole" bubbles, we address to the problem of an impurity weakly coupled to the dilute D-dimensional (D > 2) bath that undergoes the BEC transition.…”