Flavor Imprints on Novel Low Mass Dark Matter

Abstract

We present a Majorana scotogenic-like loop framework in which neutrino mass generation and dark matter stability are intrinsically connected to the breaking of the discrete flavor symmetry $A_4$. This breaking leads to the emergence of the scoto-seesaw mechanism and a $Z_2$ symmetry. This naturally explains the solar and atmospheric mass-squared differences, $\Delta m_{sol}^2$ and $\Delta m_{atm}^2$, while simultaneously ensuring dark matter stability. Our model accommodates normal ordering of neutrino masses, with a generalized $\mu$-$\tau$ reflection symmetry shaping the structure of leptonic mixing and a lower limit on the lightest neutrino mass. Moreover, the model provides predictions for the octant of ${\theta }_{23}$ and a strong correlation between $\Delta m_{sol}^2$ and $\Delta m_{atm}^2$. This correlation puts a lower bound on the fermionic DM mass. In contrast, scalar dark matter remains viable over a broad mass spectrum. A notable feature is that the low mass regime ($\sim 15$ GeV onwards) survives owing to the presence of efficient co-annihilation channels, which are typically absent in the Majorana scotogenic scenario. Additionally, the model aligns with current and future limits from lepton flavor violation experiments.

Comments: 39 pages, 10 figures, 3 tables, Matches with the published version in JHEP