Fermion production during and after axion inflation

Peter Adshead, Evangelos I. Sfakianakis

Research output: Contribution to journalArticlepeer-review


We study derivatively coupled fermions in axion-driven inflation, specifically mφ2 and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.

Original languageEnglish (US)
Article number021
JournalJournal of Cosmology and Astroparticle Physics
Issue number11
StatePublished - Nov 11 2015


  • axions
  • ination
  • leptogenesis

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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