Can a spectator scalar field enhance inflationary tensor mode?

Tomohiro Fujita, Jun'Ichi Yokoyama, Shuichiro Yokoyama

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


We consider the possibility of enhancing the inflationary tensor mode by introducing a spectator scalar field with a small sound speed which induces gravitational waves as a second-order effect.We analytically obtain the power spectra of gravitational waves and curvature perturbation induced by the spectator scalar field. We find that the small sound speed amplifies the curvature perturbation much more than the tensor mode and the current observational constraint forces the induced gravitational waves to be negligible compared with those from the vacuum fluctuation during inflation.

Original languageEnglish
Article number043E01
JournalProgress of Theoretical and Experimental Physics
Issue number4
Publication statusPublished - 2015
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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