Mass Limit for Light Flavon with Residual $Z_3$ Symmetry

Abstract

We present a modified Altarelli and Feruglio $A_4$ model where an additional $A_4$ singlet-prime flavon is introduced. In this model, non-zero ${\theta }_{13}$ is given by this additional $A_4$ singlet-prime flavon which breaks tri-bimaximal mixing. In the framework of the supersymmetry with $U(1{)}_R$ symmetry, we obtain vacuum expectation values (VEVs) and VEV alignments of flavons through driving fields. It is considered that flavon induces distinctive flavor violating process if flavon mass is light. Assuming mass of SUSY particles are sufficiently heavy so that the SUSY contributions can be negligible, we discuss the flavor violating Yukawa interaction through flavon exchange in the charged lepton sector. According to the potential analysis, the VEV of flavon breaks $A_4$ down to $Z_3$ in the charged lepton sector and relation among flavon masses is determined. Thanks for the residual $Z_3$ symmetry, many lepton flavor violating decay modes are forbidden except for $\tau \to \mu \mu \bar{e}$ and $\tau \to ee\bar{\mu }$. A mass limit of the flavon from these three-body decay modes is $60$~GeV taking into account the current experimental lower bounds at the Belle experiment. In our model, we predict a ratio of the branching ratios $\tau \to \mu \mu \bar{e}$ and $\tau \to ee\bar{\mu }$ by using known charged lepton masses. We also find that the production cross section for the flavon can be $\mathcal{O}(1)$ fb. Thus the flavon would be found at the LHC run 2 by searching for 4-tau lepton signal.

14 pages, final version

References in corpus (4)

• Observation of electron-antineutrino disappearance at Daya Bay
• Ultraviolet Completion of Flavour Models
• Predicting CP violation in Deviation from Tri-bimaximal mixing of Neutrinos
• Non-Abelian family symmetries as portals to dark matter

Cited by in corpus (8)

• Lepton-flavour-violating tau decays from triality
• Flavon-induced connections between lepton flavour mixing and charged lepton flavour violation processes
• $A_4\times U(1{)}_{PQ}$ Model for the Lepton Flavor Structure and the Strong $CP$ Problem
• Constraining $A_4$ Leptonic Flavour Model Parameters at Colliders and Beyond
• Type II seesaw supersymmetric neutrino model for ${\theta }_{13}\ne 0$
• Light flavon signals at electron - photon colliders
• Modular flavored dark matter
• Revisiting Flavor Model and Leptogenesis