Testing the Froggatt-Nielsen mechanism with lepton flavor and number violating processes

Journal Article · Wed Dec 03 00:00:00 EST 2025 · Physical Review. D.

DOI:https://doi.org/10.1103/c2ws-hx4h· OSTI ID:2520110

Cornella, Claudia ^[1]; Curtin, David ^[2]; Krnjaic, Gordan ^[3]; Mellors, Micah ^[2]

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1. European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2. Univ. of Toronto, ON (Canada)
3. Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Univ. of Chicago, IL (United States)

The Froggatt-Nielsen (FN) mechanism offers an elegant explanation for the observed masses and mixings of Standard Model fermions. In this work, we systematically study FN models in the lepton sector, identifying a broad range of charge assignments (“textures”) that naturally yield viable masses and mixings for various neutrino mass generation mechanisms. Using these textures, we consider higher-dimensional operators consistent with a FN origin and find that natural realizations predict distinct patterns in lepton flavor- and number-violating observables. For Dirac and Majorana neutrinos, FN-related correlations can lead to detectable rates of charged lepton flavor violation at next-generation low-energy experiments. Majorana and type-I seesaw models predict measurable rates of neutrinoless double beta decay. Determination of inverted neutrino mass ordering would exclude the Dirac neutrino FN scenario. Only a small minority of purely leptonic FN models predict detectable flavor violation at future muon colliders, though it is possible that a combined analysis with the quark sector will reveal motivated signals. These findings highlight the power of the FN mechanism to link neutrino mass generation to testable leptonic observables, offering new pathways for the experimental exploration of lepton number and underscoring the importance of next-generation low-energy probes.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: 89243024CSC000002; AC02-07CH11359
• OSTI ID: 2520110
• Report Number(s): CERN-TH--2024-215; FERMILAB-PUB--25-0010-T; oai:inspirehep.net:2864409; arXiv:2501.00629
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 11 Vol. 112; ISSN 2470-0010; ISSN 2470-0029
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS