Multi-field open inflation model and multi-field dynamics in tunneling

Kazuyuki Sugimura, Daisuke Yamauchi, Misao Sasaki

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


We consider a multi-field open inflation model, in which one of the fields dominates quantum tunneling from a false vacuum while the other field governs slow-roll inflation within the bubble nucleated from false vacuum decay. We call the former the tunneling field and the latter the inflaton field. In the limit of a negligible interaction between the two fields, the false vacuum decay is described by a Coleman-De Luccia instanton. Here we take into account the coupling between the two fields and construct explicitly a multi-field instanton for a simple quartic potential model. We also solve the evolution of the scalar fields within the bubble. We find our model realizes open inflation successfully. This is the first concrete, viable model of open inflation realized with a simple potential. We then study the effect of the multi-field dynamics on the false vacuum decay, specifically on the tunneling rate. We find the tunneling rate increases in general provided that the multi-field effect can be treated perturbatively.

Original languageEnglish
Article number027
JournalJournal of Cosmology and Astroparticle Physics
Issue number1
Publication statusPublished - 2012 Jan
Externally publishedYes


  • inflation
  • physics of the early universe
  • quantum cosmology
  • string theory and cosmology

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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