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Green's-function formalism for a condensed Bose gas consistent with infrared-divergent longitudinal susceptibility and Nepomnyashchii-Nepomnyashchii identity.
- Source :
-
Physical Review A: Atomic, Molecular & Optical Physics . Jul2014, Vol. 90 Issue 1-B, p1-12. 12p. - Publication Year :
- 2014
-
Abstract
- We present a Green's-function formalism for an interacting Bose-Einstein condensate (BEC) satisfying the two required conditions: (i) the infrared-divergent longitudinal susceptibility with respect to the BEC order parameter, and (ii) the Nepomnyashchii-Nepomnyashchii identity stating the vanishing off-diagonal self-energy in the lowenergy and low-momentum limit. These conditions cannot be described by the ordinary mean-field Bogoliubov theory, the many-body 7"-matrix theory, or the random-phase approximation with the vertex correction. In this paper, we show that these required conditions can be satisfied, when we divide many-body corrections into singular and nonsingular parts, and separately treat them as different self-energy corrections. The resulting Green's function may be viewed as an extension of the Popov's hydrodynamic theory to the region at finite temperatures. Our results would be useful in constructing a consistent theory of BECs satisfying various required conditions, beyond the mean-field level. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10502947
- Volume :
- 90
- Issue :
- 1-B
- Database :
- Academic Search Index
- Journal :
- Physical Review A: Atomic, Molecular & Optical Physics
- Publication Type :
- Periodical
- Accession number :
- 97599273
- Full Text :
- https://doi.org/10.1103/PhysRevA.90.013603