Strong CP problem and axion dark matter with small instantons

Ryuichiro Kitano, Wen Yin

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


The axion mass receives a large correction from small instantons if the QCD gets strongly coupled at high energies. We discuss the size of the new CP violating phases caused by the fact that the small instantons are sensitive to the UV physics. We also discuss the effects of the mass correction on the axion abundance of the Universe. Taking the small-instanton contributions into account, we propose a natural scenario of axion dark matter where the axion decay constant is as large as 1015-16 GeV. The scenario works in the high-scale inflation models.

Original languageEnglish
Article number78
JournalJournal of High Energy Physics
Issue number7
Publication statusPublished - 2021 Jul


  • Beyond Standard Model
  • Compactification and String Models
  • Cosmology of Theories beyond the SM
  • CP violation


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