### Abstract

An effective large-scale model of interacting boson gas at low temperatures is constructed from first principles. The starting point is the generating function of time-dependent Green functions at finite temperature. The perturbation expansion is worked out for the generic case of finite time interval and grand-canonical density operator with the use of the S-matrix functional for the generating function. Apparent infrared divergences of the perturbation expansion are pointed out. Regularization via attenuation of propagators is proposed and the relation to physical dissipation is studied. Problems of functional-integral representation of Green functions are analyzed. The proposed large-scale model is explicitly renormalized at the leading order.

Original language | English |
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Pages (from-to) | 105-129 |

Journal | Nuclear Physics B |

Volume | 939 |

Early online date | 21 Dec 2018 |

DOIs | |

Publication status | Published - Feb 2019 |

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### Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

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*Nuclear Physics B*, vol. 939, pp. 105-129. https://doi.org/10.1016/j.nuclphysb.2018.12.015

**Effective large-scale model of boson gas from microscopic theory.** / Honkonen, Juha; Komarova, M. V.; Molotkov, Yu. G.; Nalimov, M. Yu.

Research output

TY - JOUR

T1 - Effective large-scale model of boson gas from microscopic theory

AU - Honkonen, Juha

AU - Komarova, M. V.

AU - Molotkov, Yu. G.

AU - Nalimov, M. Yu

PY - 2019/2

Y1 - 2019/2

N2 - An effective large-scale model of interacting boson gas at low temperatures is constructed from first principles. The starting point is the generating function of time-dependent Green functions at finite temperature. The perturbation expansion is worked out for the generic case of finite time interval and grand-canonical density operator with the use of the S-matrix functional for the generating function. Apparent infrared divergences of the perturbation expansion are pointed out. Regularization via attenuation of propagators is proposed and the relation to physical dissipation is studied. Problems of functional-integral representation of Green functions are analyzed. The proposed large-scale model is explicitly renormalized at the leading order.

AB - An effective large-scale model of interacting boson gas at low temperatures is constructed from first principles. The starting point is the generating function of time-dependent Green functions at finite temperature. The perturbation expansion is worked out for the generic case of finite time interval and grand-canonical density operator with the use of the S-matrix functional for the generating function. Apparent infrared divergences of the perturbation expansion are pointed out. Regularization via attenuation of propagators is proposed and the relation to physical dissipation is studied. Problems of functional-integral representation of Green functions are analyzed. The proposed large-scale model is explicitly renormalized at the leading order.

UR - http://www.scopus.com/inward/record.url?scp=85059104874&partnerID=8YFLogxK

U2 - 10.1016/j.nuclphysb.2018.12.015

DO - 10.1016/j.nuclphysb.2018.12.015

M3 - Article

AN - SCOPUS:85059104874

VL - 939

SP - 105

EP - 129

JO - Nuclear Physics B

JF - Nuclear Physics B

SN - 0550-3213

ER -