Yukawaon Model with Anomaly Free Set of Quarks and Leptons in a U(3) Family Symmetry

TL;DR

This paper presents a yukawaon model with anomaly-free quark and lepton assignments under U(3) symmetry, leading to successful predictions of mixing parameters and neutrino mass with fewer free parameters.

Contribution

The model assigns yukawaons to the adjoint plus singlet representation of U(3), ensuring anomaly cancellation and refining parameter fitting for quark and lepton mixing predictions.

Findings

Successful prediction of quark and lepton mixing parameters.

Predicted magnitudes of CP violation in the quark and lepton sectors.

Estimated effective Majorana neutrino mass.

Abstract

In the so-called "yukawaon" model, the (effective) Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$ (yukawaons) with $3\times 3$ components. So far, yukawaons $Y_f$ have been assigned to ${\bf 6}$ or ${\bf 6}^*$ of U(3) family symmetry, so that quarks and leptons were not anomaly free in U(3). In this paper, yukawaons are assigned to ${\bf 8}+{\bf 1}$ of U(3), so that quarks and leptons are anomaly free. Since VEV relations among yukawaons are also considerably changed, parameter fitting of the model is renewed. After fixing our free parameters by observed mass ratios, we have only two and one remaining free parameters for quark and lepton mixings, respectively. We obtain successful predictions for the quark and lepton mixing parameters including magnitudes of $CP$ violation. The effective Majorana neutrino mass is also predicted.