Resonant conversions of QCD axions into hidden axions and suppressed isocurvature perturbations

Naoya Kitajima, Fuminobu Takahashi

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

We study in detail MSW-like resonant conversions of QCD axions into hidden axions, including cases where the adiabaticity condition is only marginally satisfied, and where anharmonic effects are non-negligible. When the resonant conversion is efficient, the QCD axion abundance is suppressed by the hidden and QCD axion mass ratio. We find that, when the resonant conversion is incomplete due to a weak violation of the adiabaticity, the CDM isocurvature perturbations can be significantly suppressed, while non-Gaussianity of the isocurvature perturbations generically remain unsuppressed. The isocurvature bounds on the inflation scale can therefore be relaxed by the partial resonant conversion of the QCD axions into hidden axions.

Original languageEnglish
Article number032
JournalJournal of Cosmology and Astroparticle Physics
Volume2015
Issue number1
DOIs
Publication statusPublished - 2015 Jan 1

Keywords

  • axions
  • particle physics - cosmology connection
  • physics of the early universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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