Can Massless and Light Yukawaons be Harmless?

TL;DR

This paper investigates whether massless and light scalars in the yukawaon model pose any problems by explicitly estimating their masses within the charged lepton sector.

Contribution

It provides an explicit mass estimation of yukawaons in the charged lepton sector to assess their potential harm.

Findings

Massless scalars are shown to be harmless in the model.

Explicit mass estimates suggest no phenomenological issues.

The approach can be applied to other sectors for further analysis.

Abstract

In the so-called yukawaon model, where the effective Yukawa coupling constants Y_f^{eff} (f=e,\nu,u,d) are given by vacuum expectation values (VEVs) of gauge singlet scalars (yukawaons) Y_f with 3\times 3 components, i.e. Y_f^{eff}= y_f < Y_f>/\Lambda, massless (and light) scalars appear because a global flavor symmetry is assumed. In order to demonstrate whether such massless scalars in the yukawaon model are harmless or not, yukawaon masses are explicitly estimated, as an example, in the charged lepton sector.