Unstable vacuum and fermion total reflection by the Klein step

Hiromichi Nakazato, Makoto Ochiai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The so-called Klein tunneling is re-examined within the framework of quantum field theory, but from a different point of view on the asymptotic states. We treat it as a one-dimensional scattering process of a fermion incident to a step potential and introduce asymptotic operators as appropriate t = ±∞ limits of the field operator responsible for the process. For the so-called Klein energy range, two asymptotic vacua naturally emerge which are defined as states annihilated by the asymptotic annihilation operators. They are related by a similarity transformation, which entails an unstable vacuum. When a fermion with incident energy in the Klein region is injected to the step, it is shown to be reflected with probability one, accompanied by fermion-anti-fermion pairs that are vacuum decay products.

Original languageEnglish
Article number073B02
JournalProgress of Theoretical and Experimental Physics
Issue number7
Publication statusPublished - 2022 Jul 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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