The two-field regime of natural inflation

Ana Achúcarro, Vicente Atal, Masahiro Kawasaki, Fuminobu Takahashi

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The simplest two-field completion of natural inflation has a regime in which both fields are active and in which its predictions are within the Planck 1-σ confidence contour. We show this for the original model of natural inflation, in which inflation is achieved through the explicit breaking of a U(1) symmetry. We consider the case in which the mass coming from explicit breaking of this symmetry is comparable to that from spontaneous breaking, which we show is consistent with a hierarchy between the corresponding energy scales. While both masses are comparable when the observable modes left the horizon, the mass hierarchy is restored in the last e-foldings of inflation, rendering the predictions consistent with the isocurvature bounds. For completeness, we also study the predictions for the case in which there is a large hierarchy of masses and an initial period of inflation driven by the (heavy) radial field.

Original languageEnglish
Article number044
JournalJournal of Cosmology and Astroparticle Physics
Volume2015
Issue number12
DOIs
Publication statusPublished - 2015 Dec 22

Keywords

  • axions
  • ination
  • physics of the early universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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