Thermal degree of freedom in thermo field dynamics

H. Umezawa, Y. Yamanaka

Research output: Contribution to journalArticle

14 Citations (Scopus)


The view of the thermal degree of freedom for the quantum field system, using the language of thermo field dynamics, is elaborated in this paper: the thermal degree of freedom is the degree of freedom to move through degenerate thermal vacua associated with spontaneous breakdown of a certain symmetry (Ĝ-symmetry). Based on this view, we study a quasi-particle picture, in which the Ĝ-transformation becomes the thermal Bogoliubov transformation.

Original languageEnglish
Pages (from-to)75-82
Number of pages8
JournalPhysics Letters A
Issue number2-3
Publication statusPublished - 1991 May 6
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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