Izvorni znanstveni članak
Interaction between elementary excitations in many particles boson system
Srećko Kilić
; Faculty of Sciences and Arts, University of Split, Republic of Croatia, Yugoslavia
Karmen Rivier
; Department of Electrical Engineering, University of Split, Republic of Croatia, Yugoslavia
Sažetak
We used rearranged Feenberg perturbation formula which was adopted to describe the states with two quasiparticles of the momenta ħk1→ and ħk2 →. It was noticed that two “diagrams of states” of order N° (N is the number of the particles in the system) in the fourth order perturbation term contained the interaction between particles out of the condensate. The interaction energy described by these diagrams was calculated for the potential V q = V ( -q2 + g2), ), which had the main features of the real potential between two helium atoms, and for antiparallel momenta ħk1→ = ħk2 →. It was shown that the spectrum depended on the density strongly and in particular that the interaction changed its sign and became repulsive with the increase of density. Owing to the form of the interaction diagrams, Bogoliubov summing was possible. After numerical integration we found that this approximation had a significant influence on the spectrum, although qualitative picture of the interaction was unchanged.
Ključne riječi
Hrčak ID:
332205
URI
Datum izdavanja:
7.5.1990.
Posjeta: 337 *