### Abstract

We compare many-body theories describing fluctuation corrections to the mean-field theory in a weakly interacting Bose-condensed gas. Using a generalized random-phase approximation, we include both density fluctuations and fluctuations in the particle-particle scattering channel in a consistent manner. We also separately examine effects of the fluctuations within the framework of the random-phase approximation. Effects of fluctuations in the particle-particle scattering channel are also separately examined by using the many-body T-matrix approximation. We assess these approximations with respect to the transition temperature T_{c}, the order of phase transition, as well as the so-called Nepomnyashchii-Nepomnyashchii identity, which states the vanishing off-diagonal self-energy in the low-energy and low-momentum limit. Since the construction of a consistent theory for interacting bosons which satisfies various required conditions is a long-standing problem in cold atom physics, our results would be useful for this important challenge.

Original language | English |
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Article number | 053633 |

Journal | Physical Review A - Atomic, Molecular, and Optical Physics |

Volume | 88 |

Issue number | 5 |

DOIs | |

Publication status | Published - 2013 Nov 26 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

**Comparative studies of many-body corrections to an interacting Bose-Einstein condensate.** / Watabe, Shohei; Ohashi, Yoji.

Research output: Contribution to journal › Article

}

TY - JOUR

T1 - Comparative studies of many-body corrections to an interacting Bose-Einstein condensate

AU - Watabe, Shohei

AU - Ohashi, Yoji

PY - 2013/11/26

Y1 - 2013/11/26

N2 - We compare many-body theories describing fluctuation corrections to the mean-field theory in a weakly interacting Bose-condensed gas. Using a generalized random-phase approximation, we include both density fluctuations and fluctuations in the particle-particle scattering channel in a consistent manner. We also separately examine effects of the fluctuations within the framework of the random-phase approximation. Effects of fluctuations in the particle-particle scattering channel are also separately examined by using the many-body T-matrix approximation. We assess these approximations with respect to the transition temperature Tc, the order of phase transition, as well as the so-called Nepomnyashchii-Nepomnyashchii identity, which states the vanishing off-diagonal self-energy in the low-energy and low-momentum limit. Since the construction of a consistent theory for interacting bosons which satisfies various required conditions is a long-standing problem in cold atom physics, our results would be useful for this important challenge.

AB - We compare many-body theories describing fluctuation corrections to the mean-field theory in a weakly interacting Bose-condensed gas. Using a generalized random-phase approximation, we include both density fluctuations and fluctuations in the particle-particle scattering channel in a consistent manner. We also separately examine effects of the fluctuations within the framework of the random-phase approximation. Effects of fluctuations in the particle-particle scattering channel are also separately examined by using the many-body T-matrix approximation. We assess these approximations with respect to the transition temperature Tc, the order of phase transition, as well as the so-called Nepomnyashchii-Nepomnyashchii identity, which states the vanishing off-diagonal self-energy in the low-energy and low-momentum limit. Since the construction of a consistent theory for interacting bosons which satisfies various required conditions is a long-standing problem in cold atom physics, our results would be useful for this important challenge.

UR - http://www.scopus.com/inward/record.url?scp=84890332772&partnerID=8YFLogxK

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U2 - 10.1103/PhysRevA.88.053633

DO - 10.1103/PhysRevA.88.053633

M3 - Article

AN - SCOPUS:84890332772

VL - 88

JO - Physical Review A

JF - Physical Review A

SN - 2469-9926

IS - 5

M1 - 053633

ER -