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

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

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.

Citation

Davidi, O., Gupta, R. S., Perez, G., Redigolo, D., & Shalit, A. (2018). The hierarchion, a relaxion addressing the Standard Model’s hierarchies. Journal of High Energy Physics, 2018(8), Article 153. https://doi.org/10.1007/jhep08%282018%29153

• Journal Article Type: Article
• Acceptance Date: Aug 16, 2018
• Online Publication Date: Aug 24, 2018
• Publication Date: Aug 24, 2018
• Deposit Date: Sep 6, 2018
• Publicly Available Date: Sep 6, 2018
• Journal: Journal of High Energy Physics
• Print ISSN: 1126-6708
• Electronic ISSN: 1029-8479
• Publisher: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
• Peer Reviewed: Peer Reviewed
• Volume: 2018
• Issue: 8
• Article Number: 153
• DOI: https://doi.org/10.1007/jhep08%282018%29153
• Public URL: https://durham-repository.worktribe.com/output/1349802