Non-zero U_{e3} and TeV-Leptogenesis through A_4 symmetry breaking

TL;DR

This paper explores how breaking A4 symmetry at a high scale can link TeV-scale leptogenesis with a non-zero reactor angle |U_{e3}|, consistent with neutrino oscillation data and cosmological constraints.

Contribution

It introduces a model where A4 symmetry breaking explains both neutrino mixing deviations and TeV-scale leptogenesis, connecting low-energy neutrino data with early universe baryogenesis.

Findings

Normal hierarchical neutrino spectrum is favored by WMAP data.

A sizable |U_{e3}| can produce the observed baryon asymmetry.

Non-resonance leptogenesis at TeV scale is achievable within the model.

Abstract

We consider an effective theory with an $SU(2)\times U(1)\times A_{4}\times Z_{2}\times Z_{4}$ symmetry and investigate the possibility of a linking TeV-leptogenesis with a reactor angle $|U_{e3}|$ through spontaneous $A_{4}$ symmetry breaking which is at a scale higher than electroweak scale under the framework of radiative seesaw. It has been shown that tri-bimaximal(TBM) can be obtained by forging vacuum expectation value (VEV) alignment of the $A_{4}$. Especially, one $A_{4}$ triplet scalar field with cut-off scale $\Lambda$ is added in neutrino Yukawa sector, which is responsible for the deviation of the exact TBM, to explain leptogenesis as well as a non-zero $|U_{e3}|$. Above the scale of $\Lambda$ the leptonic Yukawa sectors will lead to the exact TBM. We analyze possible spectrums of light neutrinos and their flavor mixing angles corresponding to heavy Majorana neutrino mass ordering, and show that non-resonance leptogenesis at TeV-scale constrained by low energy data is achievable, both analytically as well as numerically. We show that only normal hierarchical spectrum of light neutrino would be strongly favored by the current Wilkinson Microwave Anisotropy Probe (WMAP) data, and also show that a relatively large $|U_{e3}|$ corresponds to the value of baryon asymmetry $6.2\times10^{-10}$.