Time evolution of a quantum system in a medium and mass renormalization in the projection operator method

Tomoi Koide, Masahiro Maruyama, Fujio Takagi

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The time evolution of a quantum system in field theory is studied. We use the Shibata-Hashitsume projection operator method, which is a nonperturbative expansion method known in quantum mechanics. We calculate the time evolution of expectation values of creation and annihilation operators in a super-renormalizable model with unstable particles (or resonances) and study the initial temperature dependence. We carry out the renormalization of the ultraviolet divergence that appears in the time-dependent frequency shift using a mass counterterm. A harmless divergence of the lnt-type remains at the initial time t = 0 after mass renormalization. It is suggested that the Shibata-Hashitsume projection operator method is applicable to quantum field theory.

Original languageEnglish
Pages (from-to)373-384
Number of pages12
JournalProgress of Theoretical Physics
Volume101
Issue number2
DOIs
Publication statusPublished - 1999 Feb

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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