An A4 Model for keV-Scale Sterile Neutrino Dark Matter

We develop an A 4 Z 4 Z 2 symmetry model of neutrino masses and mixings within the minimal extended seesaw mechanism where three right-handed neutrinos R1 , R2 , and R3 and a keV-scale singlet sterile neutrino S are added to the Standard Model.This model breaks - symmetry of the neutrino mass matrix and successfully explains leptonic mixing with nonzero 13 .We study the phenomenological results of the keV-scale sterile neutrino as a dark matter candidate by calculating the relic abundance and its decay rate to active neutrinos.Significant results are also observed for solar and atmospheric mixing angles within the 3 bounds, sum of the active neutrino masses ( m i < 0.12 eV), and effective neutrino mass from neutrinoless double beta decay, m eff (0.001174-0.004367)eV for NH and m eff (0.04766-0.05088)eV for IH.