Kavli Affiliate: Satoshi Shirai
| First 5 Authors: Masahiro Ibe, Satoshi Shirai, Keiichi Watanabe, ,
| Summary:
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.
| Search Query: ArXiv Query: search_query=au:”Satoshi Shirai”&id_list=&start=0&max_results=3