### Abstract

In this paper the so-called α degree of freedom appearing in thermal quantum field theory is discussed, using thermo field dynamics (TFD). This paper is confined to stationary thermal situations, both nonequilibrium and equilibrium. The main result is that when the stationary number distribution differs from the equilibrium one the use of time ordered and antitime ordered formalisms picks up α = 1 and α = 0, in contrast to the general belief that the Feynman diagram method is usable for any other a as well. This situation in TFD will be compared with the other approaches. The reason why the Feynman diagram method becomes available for any a in the case of the equilibrium distributions is also studied.

Original language | English |
---|---|

Pages (from-to) | 370-378 |

Number of pages | 9 |

Journal | Journal of Mathematical Physics |

Volume | 33 |

Issue number | 1 |

Publication status | Published - 1992 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Organic Chemistry

### Cite this

*Journal of Mathematical Physics*,

*33*(1), 370-378.

**Heisenberg and interaction representations in thermo field dynamics.** / Evans, T. S.; Hardman, I.; Umezawa, H.; Yamanaka, Yoshiya.

Research output: Contribution to journal › Article

*Journal of Mathematical Physics*, vol. 33, no. 1, pp. 370-378.

}

TY - JOUR

T1 - Heisenberg and interaction representations in thermo field dynamics

AU - Evans, T. S.

AU - Hardman, I.

AU - Umezawa, H.

AU - Yamanaka, Yoshiya

PY - 1992

Y1 - 1992

N2 - In this paper the so-called α degree of freedom appearing in thermal quantum field theory is discussed, using thermo field dynamics (TFD). This paper is confined to stationary thermal situations, both nonequilibrium and equilibrium. The main result is that when the stationary number distribution differs from the equilibrium one the use of time ordered and antitime ordered formalisms picks up α = 1 and α = 0, in contrast to the general belief that the Feynman diagram method is usable for any other a as well. This situation in TFD will be compared with the other approaches. The reason why the Feynman diagram method becomes available for any a in the case of the equilibrium distributions is also studied.

AB - In this paper the so-called α degree of freedom appearing in thermal quantum field theory is discussed, using thermo field dynamics (TFD). This paper is confined to stationary thermal situations, both nonequilibrium and equilibrium. The main result is that when the stationary number distribution differs from the equilibrium one the use of time ordered and antitime ordered formalisms picks up α = 1 and α = 0, in contrast to the general belief that the Feynman diagram method is usable for any other a as well. This situation in TFD will be compared with the other approaches. The reason why the Feynman diagram method becomes available for any a in the case of the equilibrium distributions is also studied.

UR - http://www.scopus.com/inward/record.url?scp=0001503123&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001503123&partnerID=8YFLogxK

M3 - Article

VL - 33

SP - 370

EP - 378

JO - Journal of Mathematical Physics

JF - Journal of Mathematical Physics

SN - 0022-2488

IS - 1

ER -