Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism

Abstract The Froggatt-Nielsen (FN) mechanism successfully explains the hierarchical structure of fermion Yukawa couplings by introducing a U(1) flavor symmetry with distinct charge assignments for different fermion generations. While some FN charge assignments have been proposed, their evaluation ha...

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Main Authors: Masahiro Ibe, Satoshi Shirai, Keiichi Watanabe
Format: Article
Language:English
Published: SpringerOpen 2025-03-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP03(2025)150
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author Masahiro Ibe
Satoshi Shirai
Keiichi Watanabe
author_facet Masahiro Ibe
Satoshi Shirai
Keiichi Watanabe
author_sort Masahiro Ibe
collection DOAJ
description Abstract The Froggatt-Nielsen (FN) mechanism successfully explains the hierarchical structure of fermion Yukawa couplings by introducing a U(1) flavor symmetry with distinct charge assignments for different fermion generations. While some FN charge assignments have been proposed, their evaluation has largely relied on heuristic approaches. This paper systematically investigates viable FN charge assignments within the Standard Model, including both the quark and lepton sectors, using Bayesian statistical analysis. The study explores scenarios involving both the seesaw mechanism and dimension-five operators for neutrino mass generation. A comprehensive parameter scan over FN charges reveals a wide range of charge assignments consistent with observed fermion masses and mixing angles. Interestingly, negative FN charges and significant generational differences in charges are found to be viable, contrary to conventional assumptions. The analysis also compares the seesaw mechanism and dimension-five operator scenarios, finding no strong preference between them for optimal charge assignments. Furthermore, predictions for the lightest neutrino mass and effective Majorana mass relevant for neutrinoless double-beta decay are presented, highlighting regions of parameter space accessible to upcoming experiments. Finally, implications for nucleon decay are studied, demonstrating that different FN charge assignments predict significantly different nucleon decay lifetimes and branching ratios, providing a potential experimental probe for FN models.
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spelling doaj-art-cb5a72a935af413ebfc37138d1ed9bdd2025-08-20T03:06:48ZengSpringerOpenJournal of High Energy Physics1029-84792025-03-012025314310.1007/JHEP03(2025)150Comprehensive Bayesian exploration of Froggatt-Nielsen mechanismMasahiro Ibe0Satoshi Shirai1Keiichi Watanabe2ICRR, The University of TokyoKavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of TokyoICRR, The University of TokyoAbstract The Froggatt-Nielsen (FN) mechanism successfully explains the hierarchical structure of fermion Yukawa couplings by introducing a U(1) flavor symmetry with distinct charge assignments for different fermion generations. While some FN charge assignments have been proposed, their evaluation has largely relied on heuristic approaches. This paper systematically investigates viable FN charge assignments within the Standard Model, including both the quark and lepton sectors, using Bayesian statistical analysis. The study explores scenarios involving both the seesaw mechanism and dimension-five operators for neutrino mass generation. A comprehensive parameter scan over FN charges reveals a wide range of charge assignments consistent with observed fermion masses and mixing angles. Interestingly, negative FN charges and significant generational differences in charges are found to be viable, contrary to conventional assumptions. The analysis also compares the seesaw mechanism and dimension-five operator scenarios, finding no strong preference between them for optimal charge assignments. Furthermore, predictions for the lightest neutrino mass and effective Majorana mass relevant for neutrinoless double-beta decay are presented, highlighting regions of parameter space accessible to upcoming experiments. Finally, implications for nucleon decay are studied, demonstrating that different FN charge assignments predict significantly different nucleon decay lifetimes and branching ratios, providing a potential experimental probe for FN models.https://doi.org/10.1007/JHEP03(2025)150Baryon/Lepton Number ViolationFlavour SymmetriesTheories of Flavour
spellingShingle Masahiro Ibe
Satoshi Shirai
Keiichi Watanabe
Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism
Journal of High Energy Physics
Baryon/Lepton Number Violation
Flavour Symmetries
Theories of Flavour
title Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism
title_full Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism
title_fullStr Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism
title_full_unstemmed Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism
title_short Comprehensive Bayesian exploration of Froggatt-Nielsen mechanism
title_sort comprehensive bayesian exploration of froggatt nielsen mechanism
topic Baryon/Lepton Number Violation
Flavour Symmetries
Theories of Flavour
url https://doi.org/10.1007/JHEP03(2025)150
work_keys_str_mv AT masahiroibe comprehensivebayesianexplorationoffroggattnielsenmechanism
AT satoshishirai comprehensivebayesianexplorationoffroggattnielsenmechanism
AT keiichiwatanabe comprehensivebayesianexplorationoffroggattnielsenmechanism