Testing the Froggatt-Nielsen Mechanism with Lepton Flavor and Number Violating Processes

TL;DR

This paper investigates how the Froggatt-Nielsen mechanism can predict observable lepton flavor and number violating processes, linking neutrino mass models to experimental tests in upcoming experiments.

Contribution

It systematically analyzes FN models in the lepton sector, identifying textures that predict distinctive lepton violation signals testable in future experiments.

Findings

FN models predict detectable charged lepton flavor violation.

Majorana models suggest measurable neutrinoless double beta decay.

Inverted neutrino mass ordering can exclude certain FN scenarios.

Abstract

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.