Maki-Nakagawa-Sakata matrix and Froggatt-Nielsen mechanism

TL;DR

This paper investigates fermion flavor mixings and mass spectra within an $SU(6) imes SU(2)_R$ model, highlighting how the Froggatt-Nielsen mechanism and state-mixings produce observed neutrino mixing patterns.

Contribution

It demonstrates that the neutrino mass matrix lacks hierarchy due to seesaw cancellations, explaining large mixing angles in the MNS matrix within this model.

Findings

Neutrino mass matrix shows no hierarchy due to seesaw mechanism.

Large mixing angles in $V_{MNS}$ are successfully reproduced.

Characteristic fermion spectra patterns arise from hierarchical Yukawa interactions.

Abstract

Flavor mixings together with fermion mass spectra are studied in detail in the $SU(6) \times SU(2)_R$ model, in which state-mixings beyond the minimal supersymmetric standard model (MSSM) take place. Characteristic patterns of fermion spectra are attributed to the hierarchical structure of effective Yukawa interactions via the Froggatt-Nielsen mechanism and also to the state-mixings beyond the MSSM. It is shown explicitly that the neutrino mass matrix in the mass diagonal basis for charged leptons has no hierarchical structure. This is due to the cancellation among the hierarchical factors by the seesaw mechanism with the hierarchical Majorana mass matrix of $R$-handed neutrinos. As a consequence, $V_{\rm MNS}$ exhibits large mixing. It is found that observed values of the Maki-Nakagawa-Sakata matrix elements are reproduced successfully.