keV sterile neutrino dark matter and associated phenomenology in doublet left-right symmetric model (2502.18869v2)

Abstract: Considering the fact that no Standard Model (SM) particle can account as a suitable dark matter candidate in the relevant studies, several Beyond Standard Model (BSM) frameworks incorporate within itself some extra fields depending upon the model taken into account. Left-Right Symmetric Model (LRSM) is one such BSM framework which can successfully explain the origin of neutrino masses and also give an elaborative elucidation of the associated phenomenology like Neutrinoless Double Beta Decay $(0\nu\beta\beta)$, Lepton Flavor Violation (LFV), baryogenesis via leptogenesis etc. However, in spite of the presence of several new fields within the model, none of them can stand as a suitable dark matter candidate. This compels us to extend LRSM with extra scalars or fermions depending upon the type of study to be taken into account. In the current work, we extend LRSM with a sterile fermion per generation and the lightest of which acts as the Dark Matter (DM) candidate. The realization of the model has been done using modular symmetry, where we have used modular group $\Gamma(3)$ of weight 2 which is isomorphic to non-abelian discrete symmetry group $A_{4}$. We have then calculated the relic abundance as well the decay rate of the corresponding DM candidate and also studied $0\nu\beta\beta$ and LFV within the model and the results have been discussed in detail within the manuscript.