The hierarchion, a relaxion addressing the Standard Model's hierarchies

Oz Davidi*, Rick S. Gupta, Gilad Perez, Diego Redigolo, Aviv Shalit

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

We present a mechanism that addresses the electroweak, the strong CP, and the flavor hierarchies of the Standard Model (including neutrino masses) in a unified way. The naturalness of the electroweak scale is solved together with the strong CP problem by the Nelson-Barr relaxion: the relaxion field is identified with the pseudo-Nambu-Goldstone boson of an abelian symmetry with no QCD anomaly. The Nelson-Barr sector generates the "rolling" potential and the relaxion vacuum expectation value at the stopping point is mapped to the Cabibbo-Kobayashi-Maskawa phase. The same abelian symmetry accounts for the Standard Model's mass hierarchies and flavor textures through the Froggatt-Nielsen mechanism. We show how the "backreaction" potential of the relaxion can be induced by a sterile neutrino sector, without any extra state with electroweak quantum numbers. The same construction successfully explains neutrino masses and mixings. The only light field in our model is the relaxion, which we call the hierarchion because it is central to our construction that accounts for all the Standard Model hierarchies. Given its interplay with flavor symmetries, the hierarchion can be probed in flavor-violating decays of the Standard Model fermions, motivating a further experimental effort in looking for new physics in rare decays of leptons and mesons.

Original languageEnglish
Article number153
Number of pages32
JournalJournal of High Energy Physics
Volume2018
Issue number8
DOIs
Publication statusPublished - 24 Aug 2018

Funding

We thank Lorenzo Calibbi, Yossi Nir, and Lorenzo Ubaldi for useful discussions. The work of GP is supported by grants from the BSF, ERC, ISF, Minerva, and the Weizmann-UK Making Connections Program. Article funded by SCOAP

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

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