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Titolo:
BOUNDS FOR THE PHONON-ROTON DISPERSION IN SUPERFLUID HE-4
Autore:
BORONAT J; CASULLERAS J; DALFOVO F; STRINGARI S; MORONI S;
Indirizzi:
UNIV POLITECN CATALUNYA,DEPT FIS & ENGN NUCL,CAMPUS NORD B4-B5 E-08028 BARCELONA SPAIN UNIV TRENT,DIPARTIMENTO FIS,IST NAZL FIS MAT I-38050 TRENT ITALY SCUOLA NORMALE SUPER PISA,LAB FORUM,IST NAZL FIS MAT I-56126 PISA ITALY
Titolo Testata:
Physical review. B, Condensed matter
fascicolo: 2, volume: 52, anno: 1995,
pagine: 1236 - 1241
SICI:
0163-1829(1995)52:2<1236:BFTPDI>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
STATIC RESPONSE; LIQUID-HELIUM; EXCITATIONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
22
Recensione:
Indirizzi per estratti:
Citazione:
J. Boronat et al., "BOUNDS FOR THE PHONON-ROTON DISPERSION IN SUPERFLUID HE-4", Physical review. B, Condensed matter, 52(2), 1995, pp. 1236-1241

Abstract

The sum-rule approach is used to derive upper bounds for the dispersion law omega(o)(q) of the elementary excitations of a Bose superfluid. Bounds are explicitly calculated for the phonon-roton dispersion in superfluid He-4, both at equilibrium (rho = 0.02186 Angstrom(-3)) and close to freezing (rho = 0.026 22 Angstrom(-3)). The bound omega(o)(q) less than or equal to 2S(q) \ chi(q) \(-1), where S(q) and chi(q) are the static structure factor and density response, respectively, is calculated microscopically for several values of the wave vector q. The results provide a significant improvement with respect to the Feynman approximation omega(F)(q) = q(2)[2mS(q)](-1). A further, stronger bound, requiring the additional knowledge of the current correlation function is also investigated. Results for the current correlation function are presented.

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Documento generato il 25/11/20 alle ore 00:49:44