Gravitational waves detectable in laser interferometers from axion-SU(2) inflation

Tomohiro Fujita, Kaname Imagawa, Kai Murai

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Chromo-natural inflation (CNI) is an inflationary model where an axion coupled with SU(2) gauge fields acts as the inflaton. In CNI, the gauge fields have nonzero vacuum expectation values (VEVs), which results in the enhancement of gravitational waves (GWs). The original CNI is ruled out by the Planck observations due to the overproduction of GWs. In this work, we consider an inflationary model where the gauge fields acquire nonzero VEVs after the CMB modes exit the horizon. Moreover, we add to the model another field that dominates the universe and drives inflation after the axion starts to oscillate and the gauge field VEVs vanish. By performing numerical simulations, we find a parameter space where the enhanced GWs do not violate the CMB constraints and can be detected by the future GWs observations such as BBO and ET.

Original languageEnglish
Article number046
JournalJournal of Cosmology and Astroparticle Physics
Issue number7
Publication statusPublished - 2022 Jul 1


  • axions
  • inflation
  • primordial gravitational waves (theory)

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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