Flavoured warped axion

Quentin Bonnefoy, Peter Cox, Emilian Dudas, Tony Gherghetta, Minh D. Nguyen

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We consider a 5D extension of the DFSZ axion model that addresses both the axion quality and fermion mass hierarchy problems, and predicts flavour-dependent, off-diagonal axion-fermion couplings. The axion is part of a 5D complex scalar field charged under a U(1)PQ symmetry that is spontaneously broken in the bulk, and is insensitive to explicit PQ breaking on the UV boundary. Bulk Standard Model fermions interact with two Higgs doublets that can be localized on the UV boundary or propagate in the bulk to explain the fermion masses and mixings. When the Higgs doublets are localized on the UV boundary, they induce flavour diagonal couplings between the fermions and the axion. However, when the Higgs doublets propagate in the bulk, the overlap of the axion and fermion profiles generates flavour off-diagonal couplings. The effective scale of these off-diagonal couplings in both the quark and lepton sectors can be as small as 1011 GeV, and therefore will be probed in future precision flavour experiments.

Original languageEnglish (US)
Article number84
JournalJournal of High Energy Physics
Issue number4
StatePublished - Apr 1 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021, The Author(s).


  • Beyond Standard Model
  • CP violation
  • Field Theories in Higher Dimensions
  • Global Symmetries


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