Dark matter perspective of left-right symmetric gauge model

Abstract

We consider an incarnation of left-right symmetric model with a local gauge symmetry of SU(3)C⊗SU(2)L⊗U(1)L⊗SU(2)R⊗U(1)R. Heavy scalars and fermions present in the 27 of E6 are included in the matter sector along with the Standard Model (SM) fermions. Two such colour singlet fermions, N and LS, transforming as bi-doublet and singlet under SU(2) s respectively, can be potential candidates for Dark Matter (DM). Assignment of U(1) charges for the matter fields restricts some of the exotic fermions to interact with the SM fermions. We study in some details the prospect of such fermionic dark matters by calculating relic densities and direct detection cross-sections by treating both these particles as relics. In such a two component Dark Matter scenario, LS having smaller interaction with the SM, will dominantly contribute to relic density. However, it cannot be detected at earth bound experiments with their present sensitivity. On the contrary, N having higher rate of interaction with the SM particle has too large annihilation cross-section thus contributes very little to relic density. In fact, its interaction with the SM is too high such that N-nucleon cross-section for a wide range of N mass is higher than the experimental limits from XENON, LUX or PICO. However, such a high N-nucleon cross-section can be tamed by assuming additional dimension-6 operators involving N and SM quarks. We derive limits on the strengths of such interactions from experimental data.