Quality of the Peccei-Quinn symmetry in the aligned QCD axion and cosmological implications

Tetsutaro Higaki, Kwang Sik Jeong, Naoya Kitajima, Fuminobu Takahashi

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


We show that the required high quality of the Peccei-Quinn symmetry can be naturally explained in the aligned QCD axion models where the QCD axion arises from multiple axions with decay constants much smaller than the axion window, e.g., around the weak scale. Even in the presence of general Planck-suppressed Peccei-Quinn symmetry breaking operators, the effective strong CP phase remains sufficiently small in contrast to the standard axion models without the alignment. The QCD axion potential has small or large modulations due to the symmetry breaking operators, which can significantly affect the axion cosmology. When the axions are trapped in different minima, domain walls appear and their scaling behavior suppresses the axion isocurvature perturbations at super-horizon scales. Our scenario predicts many axions and saxions coupled to gluons, and they may be searched for at collider experiments. In particular, the recently found diphoton excess at 750 GeV could be due to one of such (s)axions.

Original languageEnglish
Article number150
JournalJournal of High Energy Physics
Issue number6
Publication statusPublished - 2016 Jun 1


  • Beyond Standard Model
  • Cosmology of Theories beyond the SM


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